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J. P. Wang, IEEE Magnetic Summer School, June 2015
Spintronics and Promising Applications
Jian-Ping Wang
University of Minnesota
IEEE Magnetic Society 2015 Summer School
June 16, 2015
J. P. Wang, IEEE Magnetic Summer School, June 2015
Early Research on Magnetism
at University of Minnesota
Prof. William Brown started his pioneer research on Magnetic Particles and laid out the foundation of
Micromagnetics Theory at the Electrical and Computer Engineering Department, University of Minnesota.
Prof. Allan Morrish started his pioneer research on high frequency magnetic materials and wrote his
famous magnetic book at the Electrical and Computer Engineering Department, Unviersity of Minnesota.
J. P. Wang, IEEE Magnetic Summer School, June 2015
John Van Vleck with his wife, Abigail,
Prof. Van Vleck was a professor at University of Minnesota.
Prof. Vleck, a Nobel Laureate, has been recognized as the father of modern magnetism.
Representative Lectures in Van Vleck Auditorium
• Albert Fert , Nobel Laureate, "Spintronics: electrons, spins, computers and telephones“ (2009)
• David Gross, Nobel Laureate, "Heterotic String Theory“ (2008)
Early Research on Magnetism
at University of Minnesota
J. P. Wang, IEEE Magnetic Summer School, June 2015
Something Interesting about ECE/UMN & Minnesota
Discovery of Micromagnetic
Theory (Brown)
Early work on perpendicular
magnetic recording (Judy)
Invention of modern
sputtering technique (Werner)
First magnetic memory (IBM)
and GMR based memory
(Honeywell)
First supercomputer (Clay)
Invention of nano-imprinting
technique (Chou)
…
Early and Large Magnetic Industry (3M,
Control Data and Seagate)
Early and Fast Growing Spintronic
Industry (Seagate, NVE, Honeywell,…)
Large Medical Device Industry
(e.g. Medtronics, …)
Mayo Clinic
…
J. P. Wang, IEEE Magnetic Summer School, June 2015
Spintronics and Promising Applications
Jian-Ping Wang
University of Minnesota
IEEE Magnetic Society 2015 Summer School
June 16, 2015
J. P. Wang, IEEE Magnetic Summer School, June 2015
Outline
Introduction
Why Spintronics (more on metallic spintronics and its hybrid)
Spintronics Basics (more on metallic spintronics and its hybrid)
Promising Applications and Challenges (selected)
Spin Memory
Spin Logic
Spin Biomedical Diagnostics
Summary and outlook
6
J. P. Wang, IEEE Magnetic Summer School, June 2015
First Invention/Concept of Amplifier of Electric Currents
Lilienfeld's patents[edit]
US 1745175 "Method and apparatus for controlling electric current" first filed in
Canada on 1925-10-22, describing a device similar to a MESFET
US 1900018 "Device for controlling electric current" filed on 1928-03-28, a thin
film MOSFET
US 1877140 "Amplifier for electric currents" filed on 1928-12-08, solid state device
where the current flow is controlled by a porous metal layer, a solid state version
of the vacuum tube
US 2013564 "Electrolytic condenser" filed on 1931-08-29, Electrolytic capacitor
In patent applications to
Canada in 1925 and to the
United States in 1926,
Lilienfeld claimed that his
solid-state amplifier “relates to
a method of and apparatus for
controlling the flow of an
electrical current between two
terminals of an electrically
conducting solid by
establishing a third potential
between said terminals.”
J. P. Wang, IEEE Magnetic Summer School, June 2015
The First Point
Contact Transistor
First Demonstration of Transistor What Can We Learn?
• A mix of team members:
− Technical manager with strong theory background and vision/passion
− A top-notch theoretical physicist
− A versatile and highly skilled experimentalist
J. P. Wang, IEEE Magnetic Summer School, June 2015 9
•Building block (device): CMOS
•Interconnection: Memory + Logic
•Computing scheme: Boolean logic, Von-
Neumann architecture
CPU Architecture(Image: Intel Core i7) Off chip DRAM memory
(Image: Micron DDR3)
CPU with embedded DRAM memory (Image:
IBM PowerPC)
Challenges of Modern Computing
J. P. Wang, IEEE Magnetic Summer School, June 2015
Challenges of CMOS
10
J. P. Wang, IEEE Magnetic Summer School, June 2015
Why Are We Looking Beyond CMOS
Nikonov / Benchmarking / NVMTS '13
0
50
100
150
200
250
300
0.0 0.3 0.6 0.9
CM
OS
Cir
cuit
De
lay
(p
s)
Supply Voltage (V)
Computation Efficiency needs max. performance at lowest supply (Vdd)
• Switching Energy a CVdd2
• At Vdd ≤ Vth , performance suffers significantly
• Lowest Vth is limited by leakage
For ITRS LG=20nm At 1nW Standby Power
J. P. Wang, IEEE Magnetic Summer School, June 2015
CMOS Device vs. Post-CMOS Devices
With further reducing device dimension, transistor based device will face
high leakage power issue.
Alternative technology (beyond CMOS) is required for future devices.
International Technology Roadmap for Semiconductors,
ITRS 2007, Executive summary
Figure Power consumption trend for CMOS
J. P. Wang, IEEE Magnetic Summer School, June 2015
Spintronics
e- e-
J. P. Wang, IEEE Magnetic Summer School, June 2015
In 1921, Otto Stern and Walter Gerlach performed an experiment which showed the
quantization of electron spin into two orientations. This made a major contribution to the
development of the quantum theory of the atom.
The actual experiment was carried out with a beam of silver atoms from a hot oven because
they could be readily detected using a photographic emulsion. The silver atoms allowed
Stern and Gerlach to study the magnetic properties of a single electron because these
atoms have a single outer electron which moves in the Coulomb potential caused by the 47
protons of the nucleus shielded by the 46 inner electrons. Since this electron has zero orbital
angular momentum (orbital quantum number l=0), one would expect there to be no
interaction with an external magnetic field.
Stern and Gerlach directed the beam of silver atoms into a region of nonuniform magnetic
field (see experiment sketch). A magnetic dipole moment will experience a force proportional
to the field gradient since the two "poles" will be subjected to different fields. Classically one
would expect all possible orientations of the dipoles so that a continuous smear would be
produced on the photographic plate, but they found that the field separated the beam into
two distinct parts, indicating just two possible orientations of the magnetic moment of the
electron.
What is Spin?
J. P. Wang, IEEE Magnetic Summer School, June 2015
Stern-Gerlach Experiment
Stern-Gerlach Experiment
J. P. Wang, IEEE Magnetic Summer School, June 2015
Spintronics and Promising Applications
Read sensor
Spin logic Spin transistor e-
e-
MRAM
Quantum
computer
New Biomedical Devices
–Sensing/Energy transfer Spin processor Field
Programmable
Gate Array
(FPGA)
J. P. Wang, IEEE Magnetic Summer School, June 2015
Types of Spin-Based Materials & Devices
e- e-
Metallic Spintronics Semiconductor Spintronics Oxide Spintronics
• Spin-transistor:
still a transistor
• Dilute magnetic
semiconductor:
Fundamental physics limit
Low spin density low
temperature
• MTJ/GMR limit:
no gain
• MTJ/GMR: need
voltage-current
conversion
• Current GMR:
low signal
• Potential limit:
speed
• Engineering limit:
processing temp
and integration with
CMOS
Non-volatility
(RT operation)
Multi-function Low power in theory
(spin current)
Multi-control
H, I, V
• To tackle the key issues for spintronic materials, devices and systems by fully taking advantages of different spintronic materials while being aware of their fundamental limits.
C-SPIN Kickoff Meeting
J. P. Wang, IEEE Magnetic Summer School, June 2015
Memory
Logic
Processor on in
Traditional Architecture
Memory Logic and
New Architecture
• Adding new functionalities is the key for future logic and
memory devices spintronic materials and devices
hold this potential.
Path to Address Challenges of Modern Computing
C-SPIN Kickoff Meeting
J. P. Wang, IEEE Magnetic Summer School, June 2015
Spin vs Magnet Spin
Magnet
Spin Injection
Spin
Channels
GMR Cu & MgO MTJ
e- e-
Charge current
Spin current
Graphene/MoS2 : 1 - 10s micrometer
Metal: 500 nanometer
Domain wall: 10s - 100s micrometer
Photonics channel: 10s millimeter
Interface
Layers of
MTJ/GMR
6/17/2015 C-SPIN Kickoff Meeting 19
J. P. Wang, IEEE Magnetic Summer School, June 2015
Opportunities for Spintronics
• Collective behavior of spin-polarized electrons coupled through different
quantum mechanisms leads to unique advantages for spintronics:
Low operation energy (in theory);
Room and high temperature operation;
Non-volatile (zero leakage power);
Re-programmable; Reconfigurable;
J. P. Wang, IEEE Magnetic Summer School, June 2015
Outline
Introduction
Why Spintronics (more on metallic spintronics and its hybrid)
Spintronics Basics (more on metallic spintronics and its hybrid)
Promising Applications and Challenges (selected)
Spin Memory
Spin Logic
Spin Biomedical Diagnostics
Summary and outlook
21
J. P. Wang, IEEE Magnetic Summer School, June 2015
Giant Magnetoresistance (GMR)
Tunnel Magnetoresistance (TMR)
Spin Transfer Torque (STT)
3 Important Discoveries in Spintronics
Grünberg/Fert
*2007 Nobel
GMR (all metals)
Free FM
Reference FM
Cu
Free FM
Reference FM
AlO or MgO
TMR (tunnel junctions)
Lower RA Higher MR
Ideal: High MR with Low RA
J. P. Wang, IEEE Magnetic Summer School, June 2015
Spin Torque: Enabler for Electrons to
Manipulate The Magnet
e-
Spin torque transfer driving device Traditional field driving device
I
H
J. C. Slonczewski, J. Magn. Magn. Mater. L1-L7, 159 (1996)
L. Berger, Phys. Rev. B. 54, 9353 (1996)
eff
0
diss HMMT M
Ga pMMT 0
STM
I
dissT dt
dMSTT MH eff
J. P. Wang, IEEE Magnetic Summer School, June 2015
Two Terminal Spin Electronics
GMR, MTJ, etc
J. P. Wang, IEEE Magnetic Summer School, June 2015
Giant Magnetoresistance
M. Baibich, J.M. Broto, A. Fert, V.D. Nguyen, F. Petroff, P. Etienne, G. Creuzet, A.
Friederich, J. Chazelas, Phys. Rev. Lett. 61, 2472–2475 (1988)
J. P. Wang, IEEE Magnetic Summer School, June 2015
Tunneling Magnetoresistance
Electron tunneling across a ferromagnet/insulator/ferromagnet junction. In (a) the
orientation of the magnetizations is parallel and (b) antiparallel, showing in both cases the
electron density of the split d states. Dashed lines show spin conserved tunneling.
I. Zutic, J. Fabian, S.D. Sarma, Rev. Mod. Phys. 76, 323–410 (2004)
J. P. Wang, IEEE Magnetic Summer School, June 2015
Spin-Dependent tunneling Conductance of
Fe|MgO|Fe Sandwiches
Zhang and Butler, Phys. Rev. B 63, 054416 (2001)
• Energy band for parallel state
Different bloch states at k//=0.
States with symmetry have the slowest decay rate. 1
J. P. Wang, IEEE Magnetic Summer School, June 2015
Spin-Dependent tunneling Conductance of
Fe|MgO|Fe Sandwiches
Zhang and Butler, Phys. Rev. B 63, 054416 (2001)
• Energy Band for Anti-parallel State
electrons decay slowly through MgO, but cannot propagate on top Fe
layer since there is no minority propagating states at the Fermi energy. 1
1
J. P. Wang, IEEE Magnetic Summer School, June 2015
MgO Barrier Magnetic Tunneling Junction
Highly-oriented
MgO (001) structure
Low roughness
Smooth interface
CoFeB > CoFe(002)
High spin polarization
+
+
Band match
Fe/MgO/Fe
> High MR ratio
Barrier (MgO (001))
Free Layer (CoFeB/..)
Fixed Layer (CoFeB/..)
Sputtering Growth:
J. P. Wang, IEEE Magnetic Summer School, June 2015
MgO Barrier Magnetic Tunneling Junction
J. P. Wang, IEEE Magnetic Summer School, June 2015
MgO Barrier Magnetic Tunneling Junction
Parkin, et al, Nature Mater. 2004;
Yuasa, et al, Nature Mater, 2004
J. P. Wang, IEEE Magnetic Summer School, June 2015
Spin Hall Effect: Beyond Two-Terminal Device
M. I. Dyakonov and V. I. Perel,; Perel' (1971). "Possibility of orientating electron spins with current". Sov. Phys.
JETP Lett. 13: 467.
J.E. Hirsch (1999). "Spin Hall Effect" (subscription required). Phys. Rev. Lett. 83 (9) 1834.
Y. Kato; R. C. Myers; A. C. Gossard; D. D. Awschalom (11 November 2004). "Observation of the Spin Hall Effect
in Semiconductors". Science 306 (5703)1910
Luqiao Liu, Chi-Feng Pai, Y. Li, H. W. Tseng, D. C. Ralph, R. A. Buhrman (2012) , Spin-Torque Switching with the
Giant Spin Hall Effect of Tantalum, Science 336 (6081) 555
J. P. Wang, IEEE Magnetic Summer School, June 2015
Liu et al., Science 336 , 55 (2012)
Magnetization Switching by Spin Hall Effect
Spin Hall Effect (SHE)
• Magnetization switching by pure spin
current.
• No charge current runs through the MTJ
stack during writing process.
• No heat generated in MTJ
e.g. Pt, Ta, W
J. P. Wang, IEEE Magnetic Summer School, June 2015
field-like
torque
Oersted
torque anti-damping
torque
Spin-orbit Torques
ˆ ˆˆ ˆ ˆ ˆ ˆ ˆ ˆ ˆ ˆ( )eff AD FL Oe
d d
dt dt a
m mm H m m y m m y m y
ADprecession
term damping
torque
Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation:
FL Oe
Spin-orbit torques
J. P. Wang, IEEE Magnetic Summer School, June 2015
Strain and Electric-Field Assisted Switching
We do need the spin torque no matter what. Strain and electric field can’t
switch the magnet but can assist the switching or lower down the energy.
J. P. Wang, IEEE Magnetic Summer School, June 2015
Metallic Spintronics
Demonstration of Room Temperature
Magnetic Tunnel Junction (MTJ)
Discovery of Giant Magnetoresistance (GMR)
Correlation between magnetic and electric performance
– anisotropic magnetoresistance (AMR)
Discovery of Magnetic Tunnel Junction (MTJ)
Theory of Spin Transfer Torque
Demonstration of Spin Transfer Torque Switching
Theory of Magnetoelectric Effect
Demonstration of Magnetoelectric Effect
Demonstration of Giant Spin Hall Effect
Proposal of MTJ/GMR Logic
Demonstration of MTJ/GMR Logic
Demonstration of Lateral Spin Valve Switching
2010 1990 1970 1900
J. P. Wang, IEEE Magnetic Summer School, June 2015
World Wide Spintronics Research Survey
1996
1998
2000
2002
2004
2006
2008
2010
2012
0 1000 2000 3000 4000
Publication
Ye
ar
Spintronic
1995 1998 2001 2004 2007 20100
200
400
600
800
1000
Public
ation
Year
USA
Japan
Europe
China
Korea
*Europe: Germany, France, UK, and Italy
• Spintronic-related publication analysis (Source: Web of
Science):
J. P. Wang, IEEE Magnetic Summer School, June 2015
A Large Tool Box for Spintronics • A variety of building blocks (not existing before) from spintronics lead to
many new devices and systems concepts and eventually new applications:
nanomagnet Skyrmion
Si ·Sj Si x Sj
Hybrid spin structure 2:
domain wall vs magnetic layer
Hybrid spin structure 1:
metal layer vs. magnetic layer
Memory cell, Logic gate,
Spin injector, RF source
Electron spin
Photon spin
angular
momentum
Spin-optical coupling ME controlled exchange bias ME controlled strain
J. P. Wang, IEEE Magnetic Summer School, June 2015
Opportunities for Spintronics • Low density STT-RAM is in production
• New and specific applications of spintronics are approaching
• Efficiency of prior switching mechanisms and related materials should be
improved greatly before approaching the 40 – 60 kBT target for drop-in
replacement
/ ME EB
Drop-in
replacement
New/Specific
applications
First
application
(STT-RAM)
J. P. Wang, IEEE Magnetic Summer School, June 2015
• Prior existing materials are insufficient for spintronics
• Different combination of those demanding new materials’ functions could
enable and lead to new applications
Beyond “Multifunctional”: Opportunities for Spintronic
Materials and Applications
Demand new heterostructured material systems
Demand new multi-functional materials
• Large perpendicular anisotropy
• 100% spin polarization ratio
• Low damping constant
• Crystalline structure and lattice match
• Bulk/Interfacial magnetism control
• TI; VCM; ME exchange bias; ME
strain
J. P. Wang, IEEE Magnetic Summer School, June 2015
Outline
Introduction
Why Spintronics (more on metallic spintronics and its hybrid)
Spintronics Basics (more on metallic spintronics and its hybrid)
Promising Applications and Challenges (selected)
Spin Memory
Spin Logic
Spin Biomedical Diagnostics
Summary and outlook
41
J. P. Wang, IEEE Magnetic Summer School, June 2015
Spin Based Memory and Computing System
J. P. Wang, IEEE Magnetic Summer School, June 2015
MTJ Memory Cell Requirements for STT-RAM application
Readability
(Signal to Noise Ratio, Read Error)
Writability
(Write Voltage,
current and time,
Write Error)
Thermal Stability
(Stand by data
Retention
Thermal Stability
under current)
R, Δ
Hk Other Requirement
• Impedance matching with CMOS circuit
• Sample to sample variation
• Endurance under voltage pressure
• STT switching distribution
e- STT-RAM memory bit
J. P. Wang, IEEE Magnetic Summer School, June 2015
Memory Technology Comparison
Source: Grandis Corporation, 2008
J. P. Wang, IEEE Magnetic Summer School, June 2015
Scaling Analysis Strategy and Simulation Scenario
for STT-RAM
with Jongyeon Kim, Yanfeng Jiang and Chris Kim, DRC 2014
J. P. Wang, IEEE Magnetic Summer School, June 2015
Scaling Challenges and Opportunities for STT-RAM
with Jongyeon Kim, Yanfeng Jiang and Chris Kim, DRC 2014
J. P. Wang, IEEE Magnetic Summer School, June 2015
Field Switching and DC Current Switching
-200 -100 0 100
0.9
1.2
1.5
1.8
2.1
Re
sis
tan
ce
(k
)
H (Oe)
RA=4.3 m2
MR=135%
Hc=48 Oe
-0.4 -0.2 0.0 0.2 0.4
0.9
1.2
1.5
1.8
2.1
-138 A
Re
sis
tance
(k
)
Current (mA)
102 A
Field switching!
DC current
switching!
Seed layer
Capping layer
PtMn 15nm
Co70Fe30 2.5 nm
Ru 0.85 nm
Co40Fe40B20 2.4 nm
MgO 0.85 nm
Co60Fe20B20 1.8 nm
130nm*50 nm
Hui Zhao, et al, J. Appl. Phys. 2011
J. P. Wang, IEEE Magnetic Summer School, June 2015
MTJ with Interface Perpendicular Anisotropy
Seed layer
Capping layer
PtMn 15nm
Co70Fe30 2.5 nm
Ru 0.85 nm
Co40Fe40B20 2.4 nm
MgO 0.85 nm
Co60Fe20B201.8 nm
Seed layer
Capping layer
PtMn 15nm
Co70Fe30 2.5 nm
Ru 0.85 nm
Co40Fe40B20 2.4 nm
MgO 0.85 nm
Co20Fe60B20 1.8 nm
Size: 50nm*130nm
With small perpendicular anisotropy
Co rich free layer
With large perpendicular anisotropy
Fe rich free layer
Size: 50nm*130nm
0 2 2c s kk dJ e M t H H Ha Theory: a is the free layer damping factor, Ms is the saturation magnetization,
Hd is the demagnetization field, Hk is the free layer perpendicular interface anisotropy field corresponding to 2Ki/Mst
48
Reduces switching current by almost a factor of 2x Nz Ms =4πMs
J. P. Wang, IEEE Magnetic Summer School, June 2015
Sub 200ps Ultrafast Switching in MTJ
49
Successfully demonstrated sub 200ps switching using in-plane MTJ sample with interface
perpendicular anisotropy. Writing energy as low as 0.12 pJ (AP-P) and 0.23 pJ (P-AP).
Free layer: Co20Fe60B20 2.0 nm
Size: 50nm*150nm
Thermal Stability: 60
Hui Zhao et al, J. Phys. D., 45,025001 (2012).
J. P. Wang, IEEE Magnetic Summer School, June 2015
3 4 5 6 7 8 9 100.0
0.5
1.0
1.5
2.0
2.5
3.0 25 C
50 C
70 C
10 ns
10 s
Sw
itchin
g P
robabili
ty D
ensity
J (MA/cm2)
x 10-6
100 ms
Temperature Dependence of
Switching Probability Distribution
50 nm×170 nm
In this particular temperature range, the switching current density variation was found be
less sensitive to the environmental temperature compared to the switching time. Hui Zhao, et al, IEEE Magn. Lett. 3, 3000304, (2012)
J. P. Wang, IEEE Magnetic Summer School, June 2015
Read Disturb Rate and Write Error Rate
Hui Zhao et al, IEEE Trans. Magn., (2012).
J. P. Wang, IEEE Magnetic Summer School, June 2015
Switching Probability Density Function Asymmetry
0 0 0
0 0
( )exp 1
exp , exp 1
p
c c
p U
Bc
tVp
V V V
t K V
k TV V
2
2
2
1 1, , 1
22 2
xx
x xf x
xwhere x e x x dt erf
a
Thermal activated switching model Skew normal distribution
Hui Zhao et al, IEEE Trans. Magn., (2012).
J. P. Wang, IEEE Magnetic Summer School, June 2015
Perpendicular STT-MRAM
Why perpendicular anisotropy?
• 1st reason Kin-plane ~ 106 erg/cm3
Kperpendicular ~ 107 erg/cm3
• 2nd reason
0
2 ( 4 )s k sc
e M V H H MI
a
0
2 ( 2 )s k s
c
e M V H H MI
a
In-plane
Perpendicular
J. P. Wang, IEEE Magnetic Summer School, June 2015
Perpendicular Spin Transfer Torque Demonstration
Electrode
Free
Cu
Fixed
Electrode
e-
Free layer: [CoFe2.5Å/Pt15Å]5 /CoFe5 Å
Space layer: Cu 30 Å
Fixed layer: [CoFe4.5 Å /Pt23 Å]7
100 nm in diameter
H. Meng and J. P. Wang, Appl. Phys. Lett., 88 (2006) 172506;
J. P. Wang, IEEE Magnetic Summer School, June 2015
MTJ with Interface Perpendicular anisotropy
Perpendicular MgO MTJ fabricated by ultrathin CoFeB layer
(<1.4 nm) as a result of perpendicular interface anisotropy in
CoFeB/MgO interface.
S. Ikeda et al Nature Mater. 9, 721 (2010)
TMR 120%, Jc0 = 3.9 x 106 A/cm2
J. P. Wang, IEEE Magnetic Summer School, June 2015
Fe16N2
< 1.5 nm CoFeB, Interface anisotropy
How to support sub-10 nm MTJ thermally stable while
keeping high MR and low damping constant?
GMR Cu & MgO MTJ
Scaling Challenges and Opportunities for STT-RAM
J. P. Wang, IEEE Magnetic Summer School, June 2015
• To search for materials that satisfy: high PMA, high spin polarization, low damping constant and good match with tunnel barriers, graphene and other spin channels
Scaling Challenges and Opportunities for STT-RAM
J. P. Wang, IEEE Magnetic Summer School, June 2015
Multi-bit STT-MRAM Concept
Four Resistance states
[1] T. Ishigaki, T. Kawahara, R. Takemura, et al., VLSI Technology Symposium, pp. 47-48, 2010 [2] Y. Zhang X. Yao and J. P. Wang, INTERMAG, GD-04, Spain, May, 2008
Four Resistance states
Fixed Layer
Free Layer 1
Fixed Layer
Free Layer 2
Free Layer 2
Free Layer 1
Fixed Layer
Multi-MTJ Multi-free layer
58
J. P. Wang, IEEE Magnetic Summer School, June 2015
Y. Zhang and J. P. Wang, Intermag 2008.
T. Ishigaki et al., Hitachi & Tohoku Univ. @ Symp. on VLSI Technology 2010
• Series Stacked MTJs
– The same film configuration provides the same JC.
– Area ratio of 2 of the two MTJs makes the IC and ΔR ratios 2 and ½.
It is difficulty to use interface anisotropy to achieve this!
Multi-bit STT-MRAM Concept
J. P. Wang, IEEE Magnetic Summer School, June 2015
Perpendicular Multi-bit MTJ Stacks
Perpendicular multi-bit MTJ stacks with: • [Co/Pd]n multilayer as the bottom electrode and the top electrode • MgO/CoFeB/Ta/CoFeB/MgO as the middle free layer
• In film stack, magnetizations of all the three layers are perpendicular. • Coercivity of the three magnetic layers are well separated.
Seed layer Ta/Pd
Bottom fixed layer
[Co/Pd]n/CFB
MgO barrier 1
Middle free layer
CoFeB/Ta/CoFeB
MgO barrier 2
Top free layer
CFB/[Co/Pd]n
Capping layer
X. Li, J. Chen, H. Li and J. P. Wang, unpublished
J. P. Wang, IEEE Magnetic Summer School, June 2015
2. E-beam or photo-
lithography to define
the nanopillar.
1. Bottom electrode
definition.
Bottom electrode
5. Via open (RIE)
Bottom electrode
6. Deposit electrodes
Current flow
MTJ MTJ SiO2 SiO2
3. SiO2 deposition (PECVD).
4. Lift off
wafer wafer
SiO2 MTJ
Bottom electrode
wafer
140nm×100nm
E-beam pillar
wafer
Bottom electrode
MTJ stack
EB resist
Bottom electrode
MTJ
wafer wafer
Bottom electrode
MTJ
EB resist
SiO2
Nanoscale Multi-Bit MTJ Fabrication
J. P. Wang, IEEE Magnetic Summer School, June 2015
Outline
Introduction
Why Spintronics (more on metallic spintronics and its hybrid)
Spintronics Basics (more on metallic spintronics and its hybrid)
Promising Applications and Challenges (selected)
Spin Memory
Spin Logic
Spin Biomedical Diagnostics
Summary and outlook
62
J. P. Wang, IEEE Magnetic Summer School, June 2015
Datta-Das Spin Transistor
Datta-Das spin transistor (1990), a device concept that has triggered the early work
on magnetic semiconductor. Non-volatility was there for the first time.
“Idealized” interfaces are not available;
Physics simply not supporting large gain; Nonlinear behavior for spin
processing is different from nonlinear behavior of electron transport;
J. P. Wang, IEEE Magnetic Summer School, June 2015
Adding New Functionalities is the Key for Designing and Building New Spin Logic Devices
Memory
Logic
Processor on in
Traditional Architecture
Memory Logic and
New Architecture (with Non-volatile components)
J.P Wang and X. F. Yao, “Programmable Spintronic Logic Devices for Reconfigurable Computation and
Beyond- History and outlook”, JOURNAL OF NANOELECTRONICS AND OPTOELECTRONICS 3, 12 (2008)
J. P. Wang, IEEE Magnetic Summer School, June 2015
Spin (Low Voltage) vs Magnet (Non-Volatile) Spin Magnet
Spin Injection
Spin
Channels
GMR Cu & MgO MTJ
e- e-
Charge current
Spin current
Graphene/MoS2 : 1 - 10s micrometer
Metal: 500 nanometer
Domain wall: 10s - 100s micrometer
Photonics channel: 10s millimeter
Interface
Layers of MTJ/GMR
Collective behavior of
coupled spins
(60 kBT vs 1000 kBT)
www.cspin.umn.edu; C-SPIN: STARnet center
J. P. Wang, IEEE Magnetic Summer School, June 2015
“Communication Between Magnetic Tunnel Junctions
Using Spin-Polarized Current for Logic Applications”, A.
Lyle, et al, IEEE TRANSACTIONS ON MAGNETICS, 46:
2216 (2010),
X. Yao, et al, “Magnetic Tunnel Junction-Based Spintronic
Logic Units Operated by Spin Transfer Torque“, IEEE Trans.
Nanotechnology (2012);
H. Meng, et al “A Spintronics Full Adder for Magnetic CPU”,
IEEE Electron Dev. Lett., 26 (2005) 360;
J. P. Wang, IEEE Magnetic Summer School, June 2015
MTJ
Input C
Input
B
Input
A I(-)
I(+)
IC
Outp
ut
A. Imre, et al.
Magnetic Cellular Automata Domain wall logic MTJ/GMR logic
D.A. Allwood, et al., H. Meng, et al
Spintronic Logic Building Blocks
J. P. Wang, IEEE Magnetic Summer School, June 2015
Comparison of Spintronic Logic Devices
CMOS
logic MQCA
Domain wall
logic MTJ/GMR logic
Element Transistor Magnetic
dot/pillar Magnetic wire MTJ/GMR
Binary states Voltage Magnetization
direction
Domain wall
(head to head;
tail to tail)
Resistance
(high, low)
Driving force Voltage Magn. field Rotating magn.
field
Magn.
Field
Pulse
current
Programmable
Reconfigurable Yes No No Yes Yes
Speed <ns <ns ns under large field < ns < ns
Density medium low low low high
Reliability high low high high high
power high high high high low
J. P. Wang, IEEE Magnetic Summer School, June 2015
H. Meng, J.G. Wang and J-P Wang, “A Spintronics Full Adder for Magnetic CPU”, IEEE Electron Dev. Lett., 26 (2005) 360
Spintronic Full Adder for Magnetic Processor
Circuit design for magnetic Full Adder based on SEVEN MTJs.
Circuit inside the dash line: the sum output (S) logic functions.
A B C 0
A B C 0
I sens
I sens
I sens
I sens
Sense
Amp
Sense
Amp
R ref 0
R ref 1 R ref 2 R ref 3
R 1 R 2 R 3
V+
V-
V+
V-
+
C1
-
-
+
S
A B C 0
C 0 C 0 C 0 A B C 0
I sens I sens
I sens I sens
I sens
J. P. Wang, IEEE Magnetic Summer School, June 2015
H. Meng, J.G. Wang and J-P Wang, “A Spintronics
Full Adder for Magnetic CPU”, IEEE Electron Dev.
Lett., 26 (2005) 360
Spintronic Full Adder for Magnetic Processor
Circuit design for magnetic Full Adder.
Circuit inside the dash line: the sum
output (S) logic functions.
Seven MTJs only
-150-100 -50 0 50 100 150
6.2
6.4
6.6
6.8
7.0
7.2
7.4
(c)
C:1
A:1
B:1
C:1
A:0
B:0
pinned layer pinned layer
Line A: 0.9Oe/mA
R(
)I (mA)
J. P. Wang, IEEE Magnetic Summer School, June 2015
Output Element Dimensions: ~238 nm x 357 nm (Aspect ratio 1.4)
Input Element Dimensions: ~190 nm x 380 nm (Aspect ratio 2)
~162 nm x 405 nm (Aspect ratio 2.5)
~142 nm x 426 nm (Aspect ratio 3)
Note: Same area for all MTJs
Si/SiO2/Ta 3/CuN 40/Ta 3/CuN 40/Ta 3/Ru 10/Ta 5/PtMn 20/CoFe30 2.4/Ru 0.85/Co60Fe20B20 2.4/MgO
1.05/Co60Fe20B20 1.6/Ta 5/Cu 10/Ru 7/Ta 10/Au 100 (nm)
Annealed at 300°C for 1 hr with field applied to set fixed layer direction
A. Lyle, J. Harms, S. Patil, X. Yao, D. Lilja, and J. P. Wang, “Direct Communication Between Magnetic Tunnel
Junctions for Non-Volatile Logic Fan-Out Architecture,” Appl. Phys. Lett., 97, 152504 (2010).
Voltage Controlled MTJ Logic
J. P. Wang, IEEE Magnetic Summer School, June 2015
-200 -150 -100 -50 0 50 100 150 200
220
240
260
280
300
320
340
360
Re
sis
tan
ce
(O
hm
s)
Applied Field (Oe)
Input
-1.9 -1.8 -1.7 -1.6 -1.5 -1.4 -1.3 -1.2
1250
1300
1350
1400
1450
1500
1550
1600
1650
Resis
tan
ce (
Oh
ms)
Applied Voltage (Volts)
111
011
001111
011
001
Voltage Controlled MTJ Logic
J. P. Wang, IEEE Magnetic Summer School, June 2015
Learning from Nanomagnet Logic
73
• First demonstration of MTJ based MQCA arrays • A. Lyle, et al., Appl. Phys. Lett., 98, 092502 (2011).
Device Type CMOS
(60nm)
MQCA
Switching energy (aJ) 216 10.1
Clock Frequency
(GHz)
4 2
Non-volatile No Yes
Throughput
(Mops/cm2/ns)
269 556
Top Contacts
Transmission
line
Coupled MTJ
Nanomagnets
• First proposal and demonstration of MQCA and logic operations • R. P. Cowburn and M. E. Welland, Science, vol. 287, pp. 1466-1468, 2000.
• A. Imre, et al., Science, vol. 311, pp. 205-208, 2006.
http://www.itrs.net/Links/2009ITRS/2009Chapters_2009Tables/2
009_ERD.pdf
J. P. Wang, IEEE Magnetic Summer School, June 2015
Experimental Details
• 50 nm x 80 nm and 70 nm x 100 nm MTJ pillars • Si / SiO2 (100 nm) / bottom lead / PtMn (20 nm) / Co70Fe30 (2.4 nm) / Ru (0.85
nm) / Co40Fe40B20 (2.4 nm) / MgO (0.9 nm) / Co60Fe20B20 (1.8 nm) / top lead
100 nm
7.5 kV WD 2.8 mm 80,000 X
Hx, Clock
100 nm
Hy, Set, Bias 100 nm
70 nm
10 nm
• Edge to edge spacing: 0 to 30 nm
• One dimensional arrays with 2 to 20 pillars that are AF coupled
J. P. Wang, IEEE Magnetic Summer School, June 2015
STT Programming: No Clocking Field
75
-100 -75 -50 -25 0 25 50 75 100
1300
1400
1500
1600
1700
1800
Re
sis
tan
ce (
Oh
ms)
HY (Oe)
Field Switching
-0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5
1300
1400
1500
1600
1700
1800
Re
sis
tan
ce (
Oh
ms)
Current (mA)
STT w/o Clock
• STT programming without clocking field analogous to STT-RAM
writing
• Demonstrates one of the worst case scenarios for programming
since no clocking field is lowering energy barrier
Hy X
I+
Iinput
1 2 3 Time
X
Hy X
I+ X
J. P. Wang, IEEE Magnetic Summer School, June 2015
5 10 15 20 25 300
200
400
600
800
1000
Nanomagnet Spacing
Cu
rren
t (
Spacing (nm)
Effect of Nanomagnet Configurations
76
0 2 4 6 8 10 12 14 16 18 20
200
300
400
500
600
# Elements in array
Cu
rren
t (
# Elements in Array
100 nm
100 nm
Spacing
# Elements
50 nm x 80 nm pillar with 10-15 nm spacing
50 nm x 80 nm pillar
J. P. Wang, IEEE Magnetic Summer School, June 2015
All Spin Logic Based on Lateral Spin Valve
CuFePtInput
magnetOutputmagnet
GND
Isolation
Contact
Channel
VSSIDC
IS
S. Datta, Nature nanotech 2010, Y. Otani, Nature physics 2008
Vsupply
Icharge, Ispin
Output magnet
spin direction
Input magnet
spin direction
Icharge
Ispin
Vsupply
77
J. P. Wang, IEEE Magnetic Summer School, June 2015
Spin Device Wish List (ASL Example)
78
Nanomagnet: High thermal stability
(must be stronger than thermal noise),
low switching energy, high polarization
Icharge Icharge
Ispin
Spin channel:
Minimal signal
attenuation
Interface:
High spin injection
efficiency (=Ispin/Icharge)
Icharge driver circuit (not shown):
Low power consumption, small
voltage drop
Isolation:
Good separation
between devices
Ground terminal:
Good
directionality
C. Kim, et al, Proceedings of IEEE, 2015
J. P. Wang, IEEE Magnetic Summer School, June 2015
ASL Energy Calculation
79
Major energy dissipation is the charge current for generating the spin current
Target device: Py+Cu ASL (i.e. Py magnet and Cu channel)
Vsupply
(CLK)
Ic, Is
tsw
System specification
m: Device count
t: Retention time
System frequency
Thermal stability
Chip failure rate
Energy barrier height
Operating temperature
Magnet material
Ms: Magnetization
α: Damping factor
P: Polarization factor
Switching energy
E=Vsupply·Q total
=Vsupply·Ic,critical·tsw
=Vsupply·Is,critical·(Ic/Is)·tsw
Magnet design
Magnetic anisotropy
Magnet dimension
Is,critical by solving LLG
Channel design
Device dimensions
Spin injection ratio (Is/Ic)
Supply voltage
Channel material
λ: Spin diffusion length
ρ: Resistivity
Impedance matching
Vsupply
IcIs
Is,critical
[1] Y. Otani, Nature physics 2008
[1]
C. Kim, et al, Proceedings of IEEE, 2015
J. P. Wang, IEEE Magnetic Summer School, June 2015 80
Test Vehicle and Thermal Stability
Channel length
Transistor count
Die size
Power
Parameter
Architecture
Characteristic
Power supply
Cache
# of cores
32nm
1 billion
216mm2
95W @ 3.4GHz
Sandy Bridge
0.7 ~ 1.15V
64KB L1 cache per core
256KB L2 cache per core
8MB L3 shared cache
4 cores
Intel Core i7 2600K processor as the
test vehicle for our system level studies
Device count for ASL system was
estimated as 0.27 billion (logic only, half
the device count of CMOS)
1. Comparison target
2. Thermal stability requirements
Eb = 69kBT at 0.01% failure rate (1FIT)
1 FIT =1 failure in 109 device-hours of operation
m(capacity): 0.27billion, t(retention time): 10yrs,
t0(attempt period): 10ns
)/exp(1
0 TkEf Bb
Relaxation time:
Thermal switching probability:
Chip failure rate:
Failure criteria:
)/exp(1)( ttP
)exp(exp10 Tk
EtmF
B
bchip
[1] S. Zhang, PRB 2004
[2] R. Takemura, JSSC 2010
[1]
[2]
FIThrhryear
110
110
2436510
0001.0
10
%01.09
9
1E-08
1E-06
1E-04
1E-02
1E+00
1E+02
55 60 65 70 75 80 8555 60 65 80
102
100
10-2
10-4
10-6
10-8
1FIT 69kBT
Thermal stability Eb/kBT
Ch
ip f
ailu
re r
ate
(%
)
70 75 85
J. P. Wang, IEEE Magnetic Summer School, June 2015 81
0
10
20
30
40
50
60
70
1 2 3 4 5 6
C0
sta
te p
ow
er
(W)
Interconnect power
Core logic power
30
50
70
20
0
60
40
10
0
5
10
15
20
1 2 3 4 5 6
C1
sta
te p
ow
er
(W)
10
15
20
5
032nm
CMOS
ASL,
λ: 2μm
Py+Cu
ASL
ASL,
λ: 2μm,
Hybrid
intercon.
ASL,
λ: 2μm,
Hybrid
intercon.,
P: 0.8
ASL,
λ: 2μm,
Hybrid
intercon.,
P: 0.8,
1μs retention
Interconnect power
Core logic power
4 cores active
1 core active, 3 cores idle
Active Power Comparison:
ASL vs. CMOS (Intel Core i7, 25MHz)
C. Kim, et al, Proceedings of IEEE, 2015
J. P. Wang, IEEE Magnetic Summer School, June 2015
Spin Hall Effect: Beyond Two-Terminal Device
M. I. Dyakonov and V. I. Perel,; Perel' (1971). "Possibility of orientating electron spins with current". Sov. Phys.
JETP Lett. 13: 467.
J.E. Hirsch (1999). "Spin Hall Effect" (subscription required). Phys. Rev. Lett. 83 (9) 1834.
Y. Kato; R. C. Myers; A. C. Gossard; D. D. Awschalom (11 November 2004). "Observation of the Spin Hall Effect
in Semiconductors". Science 306 (5703)1910
Luqiao Liu, Chi-Feng Pai, Y. Li, H. W. Tseng, D. C. Ralph, R. A. Buhrman (2012) , Spin-Torque Switching with the
Giant Spin Hall Effect of Tantalum, Science 336 (6081) 555
J. P. Wang, IEEE Magnetic Summer School, June 2015 83
J. P. Wang, IEEE Magnetic Summer School, June 2015
• Prior spintronic materials and devices are insufficient:
State-of-art for Spintronic Materials and Devices
S. Manipatruni, et al,, arXiv preprint arXiv:1301.5374
(2013).
Energy-delay trajectory for GSHE switching with PMA nanomagnet
switching
Energy-
Delay
Power
Nikonov and Young, NCN summer school, 2014
2nd phase spin logic benchmarking (through NRI centers) Perpendicular magnetic materials; thermal stability vs damping constant
Scaling
Gated magnetization switching (VCMA, Exchange Bias, Strain, etc)
Example: Strain induced/assisted magnetization switching
Gated
Energy
0 5 10 15 20 25 30
0
200
400
600
800
1000
1200
Northeasten U, NiCo/PZN-PT
NiFe(10nm)/BaTiO3
Lanzhou U, CoFeB/PMN-PT
Tsinghua U, CoFeB/PMN-PT
Northeasten U, CoFeB/PZN-PT
Nanjing U, FePd/PMN-PT
UCLA
Walther-Meibner-Institut, Ni/PZT
Str
ain
-in
du
ced
eff
ective
fie
ld (
Oe
)
E (kV/cm)
Gated
Energy
J. P. Wang, IEEE Magnetic Summer School, June 2015
Outline
Introduction
Why Spintronics (more on metallic spintronics and its hybrid)
Spintronics Basics (more on metallic spintronics and its hybrid)
Promising Applications and Challenges (selected)
Spin Memory
Spin Logic
Spin Biomedical Diagnostics
Summary and outlook
85
J. P. Wang, IEEE Magnetic Summer School, June 2015
Economic Burden on Health Care
SOURCES: Centers For Medicare and Medicaid Services,
Office of Management and Budget, Kaiser Family
Foundation, Alliance for Health Reform, Organization for
Economic Co-operation and Development, Senate Finance
Committee, Commonwealth Fund
J. P. Wang, IEEE Magnetic Summer School, June 2015
Demand for New Biosensing Technology
-Poor sensitivity
-High background noise: optical or electrical/chemical background
-Limited Multiplex
-High cost per test
-Low speed
Existing Technologies Not Ready For this Challenge
J. P. Wang, IEEE Magnetic Summer School, June 2015
GMR + Magnetic Particles Based Sensing Scheme
A) GMR sensor + capture antibodies,
biomarkers above
B) GMR sensor after specific reaction
with biomarkers
C) GMR sensor during specific
reaction with detection antibodies +
magnetic nanoparticles (MNPs)
B Other
proteins do
not react
with capture
antibodies
C
MNPs will
change the
GMR signal
after binding
A
GMR Free layer
GMR Fixed Layer
J. P. Wang, IEEE Magnetic Summer School, June 2015
Breakthrough
First publication on GMR biosensing by Naval Research Lab in 1998
• GMR sensors + Micro beads + Microfluidic channel
• No quantification
Many labs around world were unable to commercialize Naval Lab’s invention
High magnetic moment particles enabled efficient Brownian motion and low limit of detection
Unique Features for
magnetic biosensing:
1.Ultra high sensitivity
2.Ultra low background noise
(matrix-in-sensitive)
3.Multiplex (10 ~ 1000)
J. P. Wang, IEEE Magnetic Summer School, June 2015
Magnetic Tag Based Sensing Scheme
Unique Features:
1.Ultra high sensitivity
(ultra low background noise)
2.Matrix in-sensitive
3.Fast (<10 minutes)
4.Low cost (<$1.0)
5.Multiplex (10 ~ 100)
6.Low volume detection (4µL – 100 µL)
C
High resistance
No external
magnetic field
Low resistance
an external
magnetic field
C
A BPost-CMOS Technology:
Electronics > Spintronics
Nobel Prize in physics in 2007
Profs. Fert and Grunberg
Capture
antibody
Antigen (Target Molecule)
Detection antibody
+ biotin
MNP + Streptavidin
APTES-coated Sensor
J. P. Wang, IEEE Magnetic Summer School, June 2015
Magnetic Tag Based Sensing Scheme
J. P. Wang, IEEE Magnetic Summer School, June 2015
Biological testing
Integration and Computer
Control
Electrical and
Electronic system
Magnetic Field Generator and
Control
Mechanical system
Nanoparticles Functionalization
Antibody &
Antigen
Local Printing
Validation of antibody and
antigen working condition
Assay schemes
(calibration and optimization)
GMR sensor functionalization
Prototyped Handheld GMR Molecule Diagnostic System
Nanoparticles Fabrication Chemicals Local
Printing System (0.1 nanoliter)
GMR Sensor Wafer Fabrication
GMR Chip Fabrication (patterning & reaction well)
J. P. Wang, IEEE Magnetic Summer School, June 2015
Unprocessed Human Serum Quantification
NS1-5: Normal human serum sample 1-5; CS1-5: Cancer patient serum sample 1-5
[IL-6] fM NS1 NS2 NS3 NS4 NS5 CS1 CS2 CS3 CS4 CS5
ELISA 219 N/A[a] N/A[a] N/A[a] N/A[a] 192140[b] 552 742 3928 757
GMR 248 122 56 203 112 195981 567 597 3681 627
[a] N/A – Not detectable by ELISA; [b] After 80-fold dilution
Li, Y.; Srinivasan, B.; Jing, Y.; Yao, X.; Hugger, M. A.; Xing, C.; Wang, J.-P. J. Am. Chem. Soc., 2010, 132 (12), 4388–4392
J. P. Wang, IEEE Magnetic Summer School, June 2015
Z-Lab 1.0 Z-Lab 2.0
Specifications:
Power: 3.2W
Bluetooth
29 – 225 sensors per chip
4 uL sample size minimum
Specifications: Power: 0.02W
Bluetooth
29 – 225 sensors per chip
4 uL sample size minimum
www.magneticbiosensing.umn.edu
Share the Nokia
Sensing X-
Challenging
Distinguished
Winner Award with
StanfordTeam
(Shan Wang) and
other three teams
J. P. Wang, IEEE Magnetic Summer School, June 2015
To Enable Remote Healthcare System
- Personalized Medicine
Device/System/Network
Develop a disposable biochip that costs less than $1 and could test more than 100
diseases within 10 minutes.
J. P. Wang, IEEE Magnetic Summer School, June 2015
Next “Hard Disk Drive” Type
Technology in Life Science Biology
+ Magnetism
Hard Disk Drive Magnetic Biosensing
The world 2nd most difficult and
complicated engineering product;
Only three players in the world;
Minnesota is one of the places to start
this industry;
Difficult and complicated engineering
product ;
Minnesota is one of the places to start
this industry;
One of three pillars for information technologies: Processor; Display; Hard Disk Drive
Potentially one of the key technologies for disease early detection
The landscape changer for human life:
social- life internet enabler (Google,
Facebook, etc)
The landscape changer for life science
and disease early detection
J. P. Wang, IEEE Magnetic Summer School, June 2015
Magnetic Sensors Technology Comparison
J. P. Wang, IEEE Magnetic Summer School, June 2015
Outline
Introduction
Why Spintronics (more on metallic spintronics and its hybrid)
Spintronics Basics (more on metallic spintronics and its hybrid)
Promising Applications and Challenges (selected)
Spin Memory
Spin Logic
Spin Biomedical Diagnostics
Summary and outlook
98
J. P. Wang, IEEE Magnetic Summer School, June 2015
Opportunities for Spintronics • Low density STT-RAM is in production
• New and specific applications of spintronics are approaching
• Efficiency of prior switching mechanisms and related materials should be
improved greatly before approaching the 40 – 60 kBT target for drop-in
replacement
/ ME EB
Drop-in
replacement
New/Specific
applications
First
application
(STT-RAM)
J. P. Wang, IEEE Magnetic Summer School, June 2015
• Prior existing materials are insufficient for spintronics
• Different combination of those demanding new materials’ functions could
enable and lead to new applications
Beyond “Multifunctional”: Opportunities for
Spintronic Materials and Applications
Demand new heterostructured material systems
Demand new multi-functional materials
• Large perpendicular anisotropy
• 100% spin polarization ratio
• Low damping constant
• Crystalline structure and lattice match
• Bulk/Interfacial magnetism control
• TI; VCM; ME exchange bias; ME
strain
J. P. Wang, IEEE Magnetic Summer School, June 2015
C-SPIN
www.cspin.umn.edu
J. P. Wang, IEEE Magnetic Summer School, June 2015
Overview of C-SPIN
• The vision of C-SPIN is to bring together multi-disciplinary leaders in the
areas of spintronic materials, devices, circuits and architectures to create
the fundamental building blocks that allow novel spin-based multi-
functional, scalable memory and computational architectures to be
realized.
J. P. Wang, IEEE Magnetic Summer School, June 2015
C-SPIN
www.cspin.umn.edu
J. P. Wang, IEEE Magnetic Summer School, June 2015
C-SPIN PIs
CSPIN students & postdoc
Students: 121
Postdoc: 21
J. P. Wang, IEEE Magnetic Summer School, June 2015
Coordinated Effort to Go Beyond CMOS
We are excited to announce the upcoming workshop, “Heusler Alloys for Spintronic
Devices” to be held at the University of Minnesota in Minneapolis, Minnesota, July 30 – 31,
2015. The workshop will be organized by The Center for Spintronic Materials, Interfaces,
and Novel Architectures (C-SPIN).
Materials with 100% spin polarization and high perpendicular magneto crystalline anisotropy
have been the ideal for next generation spintronic memory and logic devices. Heusler alloys
are a candidate for such materials and have been extensively studied over the past decade.
There have been some promising results, but many roadblocks remain. This workshop will
candidly discuss these promises and challenges by bringing together leading experts
working in this field. To this end we expect to have around 10-15 talks over 1.5 days along
with time dedicated to discussions.
C-SPIN
PIs
C-SPIN
Students
SAB feedback and industry associates Leverage with domestic and
international collaboration
J. P. Wang, IEEE Magnetic Summer School, June 2015
Through human history, technology has
driven the advance of civilization
Recent Examples:
Car, Airplane, Space shuttle;
Computer; Internet
Processor; Hard disk drive;
Recent Nobel Prizes in Physics:
Integrated Circuits (IC)
CCD/Optical Fiber
I believe you will see more
-National Academy of Engineering
Grant Challenges White Paper
J. P. Wang, IEEE Magnetic Summer School, June 2015
Minneapolis – St. Paul Twin City
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