fermiology of bilayer colossal magnetoresistant manganites · requires research which i think is as...

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Phys.Kolloquium, TU Dresden. 26Phys.Kolloquium, TU Dresden. 26thth JuneJune,, 20072007©© Mark S. Golden 2007Mark S. Golden 2007

Mark S. GoldenMark S. GoldenVan Van derder WaalsWaals--ZeemanZeeman InstituteInstitute

Universiteit van AmsterdamUniversiteit van AmsterdamFOMFOM--AA--1111

FermiologyFermiology of of bilayerbilayercolossal colossal magnetoresistantmagnetoresistant

manganitesmanganites


OutlineOutline

ARPES as kARPES as k--space microscopyspace microscopy

Summary, conclusions and outlookSummary, conclusions and outlook

Intro. to colossal magnetoIntro. to colossal magneto--resistant resistant maganitesmaganites

bilayerbilayer systems: Lasystems: La22--2x2xSrSr1+2x1+2xMnMn33OO77

AngleAngle--resolved photoemission data:resolved photoemission data:

status quostatus quoFermi surfacesFermi surfacesquasiparticlesquasiparticlescoupling to boson coupling to boson mode(smode(s))surprises in the temperature dependencesurprises in the temperature dependence

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AmsterdamAmsterdam

Universiteit van AmsterdamUniversiteit van Amsterdam

375375 years oldyears old

2525 000 students, 2100 academic staff000 students, 2100 academic staff

'general' university 'general' university

Science FacultyScience Faculty

Van Van derder WaalsWaals--ZeemanZeeman Institute for Institute for Experimental PhysicsExperimental Physics


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Electronic, magnetic and optoelectronic Electronic, magnetic and optoelectronic properties of novel materialsproperties of novel materials

quantumquantumelectron matterelectron matter

optoelectronic optoelectronic materials materials ..

new magnetic new magnetic materials materials

and probesand probesCMPCMP

Condensed matter physics at the WZICondensed matter physics at the WZI

Anne de Anne de VisserVisser

JeroenJeroen GoedkoopGoedkoop

EkkesEkkes BrBrüückckTom Tom GregorkiewiczGregorkiewicz

Mark GoldenMark Golden

YingkaiYingkai HuangHuang


Quantum Quantum mattersmatters

macroscopic 'laboratories' for quantum macroscopic 'laboratories' for quantum microscopicsmicroscopics

novel, multifunctional materialsnovel, multifunctional materials

unconventional quantum matter is undergoing a worldunconventional quantum matter is undergoing a world--wide boom:wide boom:

quantum phase transitionsquantum phase transitionsquantum criticalityquantum criticality

ambitious intellectual joint venture:ambitious intellectual joint venture:experiment & theoryexperiment & theory

electronelectronatomatom quantum matterquantum matter

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What's emerging ?What's emerging ?

"at each new level of "at each new level of complexitycomplexity, , entirely new properties appear, and entirely new properties appear, and the understanding of these the understanding of these behavioursbehavioursrequires research which I think is as requires research which I think is as fundamental in its nature as any fundamental in its nature as any other."other."

P.W. Anderson, Science, 1972 P.W. Anderson, Science, 1972

simple building blockssimple building blocks

wellwell--known rules (QM)known rules (QM)

wholly wholly unexpectedunexpectedpropertiesproperties

VU

MIT

VU

MIT


'Axis of complexity' 'Axis of complexity' Piers ColemanPiers Coleman: Ann. Henri Poincaré 4 (2003) 1

not not ifif new phenomena will be discoverednew phenomena will be discovered

but but whenwhenwhere should one start looking first...?where should one start looking first...?

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Complexity Complexity →→ emergenceemergence

(almost by definition) experiment led(almost by definition) experiment led

creatingcreating unconventional quantum matter:unconventional quantum matter:

imagingimaging unconventional quantum matter:unconventional quantum matter:

in kin k-- or qor q--space (charge and/or spin)space (charge and/or spin)

in real spacein real space

in timein time understandingunderstanding

controlcontrol

no synthesis = no synthesis = no progressno progress

atoms + lasers: e.g. optical lattice matteratoms + lasers: e.g. optical lattice matter

atoms + chem. bonding: e.gatoms + chem. bonding: e.g. .


rr--space @ VTspace @ VT--STMSTMUHV, CreatecUHV, Createc

Advert:Advert: real space microscopy (STM / STS)real space microscopy (STM / STS)

Alex Groot, Freek Massee, Marco Gobbi

+ J.B. Goedkoop+ J.B. Goedkoop

HOPGHOPG

Si (7x7)Si (7x7)

(Pb,Bi)(Pb,Bi)--22122212BiBi--22122212

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OutlineOutline








Photoemission: a 'high' energy probePhotoemission: a 'high' energy probe

! High energy !! High energy !high energyhigh energy means 'sudden'means 'sudden'→→ simple to interpretsimple to interpret

photocurrent photocurrent vs.vs. EEkinkin and and angles angles θ,φθ,φ

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)(),(,

2εε fkAiApfI

if∑ •∝

rr

matrix element Fermi function

ARPES : ARPES : physical quantity measuredphysical quantity measured

self energy: imaginary part

self energy: real part

spectral function

[ ] [ ]22 ),("),('),("1),(

εεεεε

πε

kkkkA

k Σ+Σ−−Σ=

hhννabsolute kabsolute k||||kk⊥⊥polarisationpolarisation

temperaturetemperature


Our goal: the spectral functionOur goal: the spectral function

pic: after Meinders

nonnon--interacting systeminteracting system interactions oninteractions on

QPQP

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ARPES:ARPES: shopping listshopping list

SLSSLS

pic: SPring8

Dam

asce

lli

UvA / PSIUvA / PSI


Dam

asce

lliPhotoemission data: Photoemission data: structurestructure

||

EDMEDM

ReΣ

E-EF

Inte

nsity

EF

0

EDCEDC

MDCMDC

width in k2·ImΣ

9


OutlineOutline








Potted history: colossal Potted history: colossal magnetoresistantmagnetoresistant manganitesmanganites

1969:1969:Searle & Wang, Can. J. Phys. 47, 2701 (1969)Searle & Wang, Can. J. Phys. 47, 2701 (1969)

LaLa11--xxPbPbxxMnOMnO33 -- giant (negative) giant (negative) magnetoresistancemagnetoresistancenear near TTCurieCurie

Essential theory:Essential theory:ZenerZener (1951), Anderson & Hasegawa (1955), de (1951), Anderson & Hasegawa (1955), de GennesGennes (1960)(1960)

double exchangedouble exchange

particular filling of the dparticular filling of the d--orbitals of the orbitals of the MnMn ionion++

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Ligand fieldsLigand fields

tt2g2g

ππ--bonding to bonding to ligandsligands

eegg

σσ--bonding to bonding to ligandsligands

picspics: : orbitronorbitron


MnMn valencyvalency: between 3 and 4: between 3 and 4

e.g. Lae.g. La0.670.67SrSr0.330.33MnOMnO33

0.67 x La0.67 x La3+3+

0.33 x Sr0.33 x Sr2+2+

3 x O3 x O22--

1 x Mn1 x Mn3.33+3.33+

0.670.67 1 1 11 1 1

3.67 Mn3d electrons3.67 Mn3d electrons

high spinhigh spin

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Double exchangeDouble exchange

ee ggel

ectro

n op

erat

or,

elec

tron

oper

ator

, ccii σσ

σσii localisedlocalised tt2g2g spin spin operators operators

JJHH onon--site FM site FM coupling between coupling between eegg spin and the tspin and the t2g2g

local spin (local spin (σσ))

t hopping of t hopping of eegg

electrons from one electrons from one MnMn site to nextsite to next


Double exchangeDouble exchange

if if Hund'sHund's rule energy, J (rule energy, J (expexptt..: 2eV) > bandwidth, W: 2eV) > bandwidth, W

tteffeff = = t t coscos ((θ θ /2)/2)-- eegg spin always parallel to the tspin always parallel to the t2g2g spins and spins and -- θθ: angle between the t: angle between the t2g2g spins of the spins of the neighbouringneighbouring Mn'sMn's

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RuddelsonRuddelson--Popper series (variations on Popper series (variations on perovskitesperovskites))

pic: Matt Rosseinsky


Colossal (negative) Colossal (negative) magnetoresistancemagnetoresistance: CMR: CMR

double exchangedouble exchange means: means: ferromagnetic (FM) situation ferromagnetic (FM) situation favoursfavours hoppinghopping

in plane

out of plane

T. Kimura and Y. Tokura, Annu. Rev. Mat. Sci., 2000

quasi 2D structurequasi 2D structure→→ anisotropy in c and anisotropy in c and abab transport:transport:

CMR

CMR effects of 4000%CMR effects of 4000%

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BilayerBilayer managanitesmanaganites

pic: Matt Rosseinsky

La,Sr,Orock salt

blocksdouble

MnO2planes

reduced dimensionalityreduced dimensionality

greater role for fluctuationsgreater role for fluctuationsconnection to theconnection to thehigh high TcTc cupratescuprates ??strong anisotropystrong anisotropy

(even) larger CMR effect(even) larger CMR effect

cleavagehere

cleavage surfaces suitablecleavage surfaces suitablefor surface sensitive probes:for surface sensitive probes:

ARPESARPESSTM / STSSTM / STS


TT,,xx phase phase diagrammediagramme

Hole doping, x

LaLa22--2x2xSrSr1+2x1+2xMnMn22OO77

LaLa22SrSr11MnMn22OO7 7 as 'parent insulator', as 'parent insulator', xx gives no. of additional holesgives no. of additional holes

why sowhy socomplex ?complex ?

Pic

ture

from

: Lin

g et

al.

PR

B 6

215

096

(200

0)

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Spins Spins ↔↔ charges charges ↔↔ orbitals (lattice)orbitals (lattice)

JahnJahn--Teller distortionsTeller distortions

select the select the eegg orbitalorbitaloccupancyoccupancy


Spins Spins ↔↔ charges charges ↔↔ orbitals (lattice)orbitals (lattice)

orbital ordering orbital ordering

strain reduction strain reduction

magnetic order:magnetic order:within MnOwithin MnO22 plane, within plane, within bilayerbilayer, inter, inter--bilayerbilayer

charge orderingcharge ordering

MnMn3+3+ -- MnMn4+4+ -- MnMn3+3+ -- MnMn4+4+

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TT,,xx phase phase diagrammediagramme

Hole doping, x

LaLa22--2x2xSrSr1+2x1+2xMnMn22OO77

Focus here:• FM metallic ground state

• CMR effect • max. Tc

Pic

ture

from

: Lin

g et

al.

PR

B 6

215

096

(200

0)

??


Campbell, PRB2001

PolaronsPolarons, CO, OO above , CO, OO above TTcc

double exchange not sufficient for explaining PI phasedouble exchange not sufficient for explaining PI phase

polaronspolarons ((polaronicpolaronic correlations) above correlations) above TcTcOO and/or CO correlationsOO and/or CO correlationsstripeynessstripeyness

complex interplay of charge, spin, orbital degrees of complex interplay of charge, spin, orbital degrees of freedom still not understoodfreedom still not understood

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OutlineOutline








OutlineOutline







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Expectations from band structure calculationsExpectations from band structure calculations

DFT says: DFT says: halfhalf--metallic metallic ferromagnetferromagnet2001

Pics from: Huang et al. PRB 62 13318 (2000)

X

M

Γ

Majority band: quasi-2D Fermi surface

3dx2-y2 BB

3dx2-y2 AB

3dz2-r2

eegg bandwidth: bothbandwidth: both3dx2-y2 and and 3dz2-r2 are occupiedare occupied


ARPES of 2L ARPES of 2L manganitesmanganites: : historyhistory

Colorado group:Colorado group:

ghost Fermi surface, pseudogapghost Fermi surface, pseudogapDessau Dessau et al.et al., PRL1998, PRL1998data: data: x=0.4x=0.4

Fermi surface nesting Fermi surface nesting (no(no QP'sQP's anywhere)anywhere)Chuang Chuang et al.et al., Science 2001, Science 2001datadata: : x=0.4x=0.4

hhνν=50eV=50eVintegrated integrated ±±200meV of E200meV of EFF

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ARPES of 2L ARPES of 2L manganitesmanganites: : status quostatus quo

general statement 2L general statement 2L manganites: manganites: nodalnodal metalmetal(Fermi arc)(Fermi arc)data: data: x=0.4x=0.4

StanfordManella et al. Nature (2005)

ColoradoZ. Sun et al. PRL (2006)

QP'sQP's at at antinodeantinodeno no QP'sQP's forfor x=0.4x=0.4data: data: x=0.36x=0.36, 0.38, 0.4, 0.38, 0.4


ARPES of 2L ARPES of 2L manganitesmanganites: : status quostatus quo

ColoradoZ. Sun et al. Nature Physics (2007)

metallicity above metallicity above TTcc(phase separation)(phase separation)data: data: x=0.38, AB bandx=0.38, AB band

TTcc

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aa

Enter Amsterdam. Enter Amsterdam. Crystal characterisation: x=0.36Crystal characterisation: x=0.36

sharp transitions, excellent cleavage surfacessharp transitions, excellent cleavage surfaces

FMFM--MM PMPM--II

TTcc = 130K= 130K


Step 1: QP at Step 1: QP at antinode (antinode (ππ/a,0),/a,0), or not ?or not ?

S. de Jong et al. cond-mat/0611287Nov 2006 & W.K. Siu, MSc thesis 2006

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Step 2: Step 2: And betweenAnd between ((ππ/a,0) and/a,0) and BZ diagonal ?BZ diagonal ?

S. de Jong et al. 2006

FS map (EF± 15 meV)T= 30K, hv= 56eV. AB band only.

clear AB FS: clear AB FS: resembles LDA, resembles LDA, moderately nestedmoderately nested


X

Γ1234567

Hunting down the QP'sHunting down the QP's

low energy spectral weight alllow energy spectral weight all round the round the ABABFermiFermi surfacesurface


hhνν=56eV=56eV

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EnergyEnergy distribution distribution curvescurves

note:note:'QPs''QPs' at all at all kkFF's's for LSMOfor LSMO


peaks not yet peaks not yet resolution resolution limited……limited……

hhνν=56eV=56eV



antibonding band:antibonding band:sharp QP, resolution limited widthsharp QP, resolution limited width

µµ -- ARPES: AB band ARPES: AB band (at the SLS)(at the SLS)

hhνν=56eV=56eV

at (at (ππ/a,0)/a,0)

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S. d

e Jo

nget

al.

2006

bonding band:bonding band:sharp QPsharp QP? extra feature? extra feature

bonding band:bonding band:EEFF MDC width (0.07 MDC width (0.07 ππ/a) is double that of the AB band/a) is double that of the AB band

hhνν=73eV=73eV


µµ -- ARPES: BB band ARPES: BB band (at the SLS)(at the SLS)


S. d

e Jo

nget

al.

2006

What about the BZ diagonal ?What about the BZ diagonal ?

FWHMFWHM0.07 0.07 ππ/a/a

FWHMFWHM0.1 0.1 ππ/a/a

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kkFF EDC'sEDC's

S. d

e Jo

nget

al.

2006

for x=0.36: for x=0.36:

QP's visible for:QP's visible for:

AB FS at (AB FS at (ππ/a,0) /a,0) andand zone zone diagonal diagonal

and and for BB FS at (for BB FS at (ππ/a,0)/a,0)

((ππ/a,0)/a,0)

((ππ/a,0)/a,0)

BZ diagonalBZ diagonal



coupling to collective (bosonic) mode(s):coupling to collective (bosonic) mode(s):clear deviation from nonclear deviation from non--interacting dispersion between 60 and 110meVinteracting dispersion between 60 and 110meValso seen in MDC width (also seen in MDC width (→→ QP inverse lifeQP inverse life--time)time)

Renormalisation effects at (Renormalisation effects at (ππ/a,0)/a,0)

T=30KT=30K

Width (π/a)0.200.150.10

-0.3

-0.2

-0.1

0.0

Position (π/a)0.200.10

-0.3

-0.2

-0.1

0.0

E-E

F(eV

)

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OutlineOutline





history, statushistory, status quoquoFermi surfacesFermi surfacesquasiparticlesquasiparticlescoupling to boson coupling to boson mode(smode(s))surprises in the temperature dependencesurprises in the temperature dependence


Temperature dependence at (Temperature dependence at (ππ/a,0)/a,0)S

. de

Jong

et a

l.20

06

TTCC=130K=130K

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TT--dependence: renormalisation effects (dependence: renormalisation effects (ππ/a,0)/a,0)


peak position (kpeak position (kyy)) MDC FWHM (MDC FWHM (ππ/a)/a)(offset)(offset)

T=30T=30T=95T=95T=145T=145

hhνν=56eV=56eV


E-E

F(eV

)


TT--dependence:dependence:MDC width at (MDC width at (ππ/a,0)/a,0)

S. de Jong et al. 2006MDC FWHM (MDC FWHM (ππ/a)/a)

T=30T=30T=95T=95T=145T=145

hhνν=56eV=56eV

at (at (ππ/a,0)/a,0)strong Tstrong T--dependence for dependence for low energieslow energies

change in form change in form within FMwithin FM--M phase M phase (30 (30 →→ 95K)95K)

E-E

F(eV

)

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TT--dependence: at (dependence: at (ππ/a,0) and BZ diagonal/a,0) and BZ diagonal

S. de Jong et al. 2006TTcc

hhνν=56eV=56eV


BZ diagonalBZ diagonal


TT--dependence: dependence: kkFF EDC's at (EDC's at (ππ/a,0) and BZ diagonal/a,0) and BZ diagonal


giant temperature dependence. kgiant temperature dependence. k--dependent.dependent.QP peak more robust an antinodeQP peak more robust an antinodespectral weight shift even larger at nodespectral weight shift even larger at node

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TT--dependence: metallic phase above dependence: metallic phase above TTcc ??

T30T30--T95T95

T95T95--T145T145

two phase model doesn't two phase model doesn't work herework here-- QP peak only for T<TcQP peak only for T<Tc-- different high E behaviour for the different high E behaviour for the two ktwo k--points points


Some (founded) speculationsSome (founded) speculations

X

M

Γ

orbital fluctuations ?orbital fluctuations ?should be strong near 'FS approach' along diagonalshould be strong near 'FS approach' along diagonal

kk--dependence ofdependence ofTT--dep?dep?

relative supression of spectral relative supression of spectral weight at node ?weight at node ?

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phase separation (also above Tc) ?phase separation (also above Tc) ?Aarts, MydoshAarts, MydoshLSMO, 113LSMO, 113

RRøønnow nnow et al., LSMO 327, x=0.3et al., LSMO 327, x=0.3



phase separation and photoemission data ?phase separation and photoemission data ?

Fermi step also well above Tc Fermi step also well above Tc

kk--dependence of spectra vs. dependence of spectra vs. temperature temperature

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ConclusionsConclusions

no such thing as a (general) nodal metalno such thing as a (general) nodal metal

quasiparticles are to be found on both the AB (at quasiparticles are to be found on both the AB (at zone face zone face andand diagonal) and BB Fermi surfaces diagonal) and BB Fermi surfaces for x = 0.36for x = 0.36

strong renormalisation effects clearly identified:strong renormalisation effects clearly identified:-- phononphonon--orbitons orbitons -- strongly Tstrongly T--dep.: magnetism dep.: magnetism

anomalous temperature dependence:anomalous temperature dependence:-- huge shifts of spectral weighthuge shifts of spectral weight-- can't fit a 2can't fit a 2--phase modelphase model

analysis underwayanalysis underway


Glimpse of something hot off the beamline......Glimpse of something hot off the beamline......

hhνν=56eV=56eV


X

M

Γ

30


0 0.5 1.0 1.50 0.5 1.0 1.5

Glimpse 2Glimpse 2 hhνν=73eV=73eV


X

M

Γ


? possible breakdown of 100% spin polarisation ?? possible breakdown of 100% spin polarisation ?

minority (LSDA) majority (LSDA)minority (LSDA) majority (LSDA)

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0 0.5 1.0 1.50 0.5 1.0 1.5

Glimpse 2Glimpse 2 hhνν=73eV=73eV



Quantum Electron Matter GroupQuantum Electron Matter Group, University of Amsterdam, University of AmsterdamSanne de Jong, Yingkai Huang, WingSanne de Jong, Yingkai Huang, Wing KiuKiu SiuSiu, , ImanIman SantosoSantoso, , WimWim KoopsKoops, , Freek Massee, Ton GortenmulderFreek Massee, Ton Gortenmulder

SLSSLSVladimir Vladimir StrocovStrocov, Luc , Luc PattheyPatthey, Ming Shi , Ming Shi

Support at BESSYSupport at BESSYRolf Follath, Patrick BresslerOlaf Schwarzkopf

FundingFundingFOM, EU, UvA

The CreditsThe Credits

Sanne de JongSanne de Jong

Yingkai HuangYingkai Huang

fermiology of bilayer colossal magnetoresistant manganites · requires research which i think is as...

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