ENHANCEMENTS 2008-2009 I. Completed addition of 10T-10 mK facility --- annex to Microkelvin Laboratory fast turn-around, test samples, cells prior to use in ultra-low temperature High B/T Facility (0.25mk, 16 T)

II. Extended NHML user to Bay 2 of Microkelvin Laboratory (0.05mk, 8T). Seeking research scientist to provide needed staff

III. In Progress: New 20T magnet(Cryomagnetics Inc.) Aug. completion of inner-most Nb3Sn insert coilSep. completion of all Nb3Sn coils Oct. Completion of 20 T and demag coil setNov.-Dec. Final assembly and testingDelivery ---- end of Dec. 2009

NHMFL High B/T Facility - Gainesville

Schematic View of the High-B/T Facility

CAPABILITIES: Method for Highest B/T

• Scientific Mission of the Facility Dedicated to high-B experiments requiring T< 20 mK

Experiments generally require a quiet environment and/or a long cooling time.

• High Magnetic FieldB = 15.3/16.5 T ( upgrade to 20 T, 2009 Homogeneity 1.6x10-5 10 mm DSV

< 3x10-3 over 100 mm axial length 30 mm-dia bore, 25 mm-dia experimental space

• Ultra-Low Temperature 5 mole PrNi5 (nuclear refrigerant), Tmin < 0.4 mK 8 nW cooling power, t > 6 weeks @ 1 mK

(world’s largest)

Instrumentation

• Capabilities and Specialized Instruments Electrical Transport Measurements High frequency Pulsed NMR (300 MHz – 1.6 GHz) Ultrasound

High sensitivity bridgesVibrating-wire viscometersSample rotator (–10 to +90, with a liq-3He actuator)

Low temperature RF pre-amplifier -- NMR applications

• ThermometryPt NMR T < 20 mK, in low B space3He melting curve thermometer 0.4 mK < TVibrating-wire thermometer 1.7 mK < TKapton capacitance thermometer 4 mK < T

CMN susceptibility thermometer 15 mK < T, in low B space RuO2 resistor (all commercial) 20 mK < T, in low B space

rotatorheat exchanger

sample

Rotator

HIGH B/T CAPABILITIES: Ultra-Low T ROTATOR

HIGH B/T Instruments: NMR CellHIGH B/T CAPABILITIES: NMR Cell

NMR up to 16 T :

Studies of quantum diffusion of 3He in superfluid 4He for high nuclear spin polarization.

Re-entrant cavity with walls at relativelyhigh temperature and sample in cold finger inside cavity

HIGH B/T Instruments: NMR CellNEW CAPABILITIY: LOW

TEMPERATURE AMPLIFIER

C. Huan, et al. J. Low Temp Phys. (in press)

Uses HEMT transistor (simple source follower) can operate to ~ 0.3 K

T Noise ≤ 1 K

First application: low frequency NMR at ultra-low T

Crossed-Coil NMR Probe:low frequency, low gamma

S. S. Kim, C. Huan et al.J. Low Temp. Phys. (in press)

Pulse B1, create transverse Magnetization in receiving coil

amplifier standoffs

NMR cell

2008-2009 Users and Experiments 1. FQHE of n=5/2 and 7/2 States in High Density Sample.

W. Pan (Sandia Nat. Lab.), D.C. Tsui (Princeton)

2. Supersolid 4He and NMR of 3He ImpuritiesD. Candela et al. (U. Mass.).

3 & 4. BEC and Quantum Phase Transitions in S=1 Antiferromagnet.V. Zapf et al. (LANL)

5. Charge Carrier Density Variation 5/2 Fractional Quantum Hall Effect

W. Pan (Sandia )D. Tsui (Princeton University)

6.Systematic investigation of the metal-insulator transition at ultra low temperatures in p-type GaAs FET structures.

  D. Luhman, D.C. Tsui (Princeton Univ.)

7. Magnetic Interactions of Novel Materials at Low T/High B.M.W. Meisel (UF), A. Feher et al. (Šafárik Univ., Košice, Slovakia).

8. Search for long-range magnetic order in weakly coupled quantum S=1/2 chain system

T. Hong and A. Zheludev, NSSD, ORNL

9.High sensitivity dielectric measurements supersolid 4HeM. Chan et al. Penn State U.

Bay 3

Bay2

Bay 3

Wm Annex

Wm AnnexBay 3 &

Wm Annex

Wm Annex

2009 Future Users and Experiments

1. Magnetization Studies of NFL Ground State of CeCoIn5

A. McCollam & S.R. Julian (U. Toronto)

2.Dielectric susceptibility studies of supersolid 4HeM. Chan, (PSU), L. Yin et al. (UF)

3. Search for Half-Metallic Ground State in Quasi-One Dimensional MagnetXiao-Dong Wen, Thomas J. Cahill, Roald Hoffmann (Cornell) Bin Zhang (Chinese Academy of Sciences)

4. Studies of Magnetic PN Junctions . N. Rangaraju, B. Wesson (NthWestern Univ.)

5. Quantum Tunneling in Molecular Magnets

N. Dalal (FSU)

6. Two-dimensional metallic states –GaAs Quantum Wells)S. Tozer et al. (FSU, NHMFL)

7. High B Studies of Paramagnetically Doped materialsM.H. Levitt, Univ. of Southampton)

Bay 2, Oct. 09

Request/Proposal in Prep.

Wm Hall Annex, Sep. 09

Interest/Proposal Pending

Interest/Proposal Pending

Bay 3, Jan.? 09

Interest/Proposal Pending

NMR Studies of Dilute 3He in Solid 4He and Test of proposed Supersolid state.

D. Candela (Univ. of Massachusetts), Sung Su Kim, Chao Huan, Liang Yin, Jian-sheng Xia et al. University of Florida and NHMFL.

Science Highlights 1

NMR measures quantum tunneling of 3He impurities in solid 4He:

Low T values of T2 give 3-4 quantum exchange rates: Strongly dependent on impurity concentration interaction V=Vo/Rn

S. S. Kim, C. Huan et al., J. Low Temp. Phys. (in press)

Support: NHMFL Collab. Grants Res. Program

short range -- best fit

long range

Interplay of Frustration and Magnetic Field in 2D Quantum Antiferromagnet

A. Orendáčová et al., University, Košice, Slovakia; M. W. Meisel et al., NHMFL.

A. Orendáčová et al., PRB (submitted), arXiv:0906.3181

Acknowledgements: VEGA (1/0078/09, APVV-0006-07), ESF RNP , NSF DMR-0701400, DMR-0654118, State of Florida, Deutsche Physikalische Gesellschaft (DPG), EuroMagNET II, US Steel Košice s.r.o.

Science Highlights 2

 

BKT calculation (Cuccoli et al. PRB 68 (2003)).χac at NHMFL-UF Wm 123 Facility.

All other symbols from Cv analysis.

Cu(tn)Cl2 (tn = C2H10N2): S = ½ anisotropic 2D highly frustrated magnet: square lattice with nn J (= 3 K), frustrating nnn J′ (< 0.6 J), weak interlayer J′′ (~ 10−3 J)

Test BKT model for ideal square lattice:vortex-antivortex (V-AV) binding at low T,B with transition to spin gap at Bsat

High B/Low T susceptibility measurements

Heat capacitiesstructure idealized

peak

Max.

Bose-Einstein Condensation Universality Class NiCl2- 4SCs(NH2)2 at Ultra-Low T

V.S. Zapf L. Yin et al. , A. Padhuan-Filho

Science Highlights 3

Ni S=1 spins: 3D XY anti-ferromagnet--- critical fields: Hc1 ~ 2 T, Hc2 ~12 T.

Expect power-law T dependence:

Hc1(T) -- Hc1(0) = aT with = 1.5

Confirmed at mK temperatures with a=1.470.01

Unit cell of tetragonal NiCl2–4SCs(NH2)2

AC susceptibilty measurements, NHMFLHigh B/T facility

L. Yin et al., Phys. Rev. Lett. 101,187205 (2008)

Disorder driven gapless superfluid in high porosity aerogel : Ultrasound measurements

Y. Lee et al., Phys. Rev. Lett. 98, 225301 (2007).

)1()()( ffNNd Sharma and Sauls, Physica B (03)

?Tunneling exp. cannot be done for superfluid.

BUT-dependence of

ultrasound attenuation can provide similar info.

Science Highlights 4

Growth of Users and CostsHigh B/T Facility (2005-2009

Liquid helium costs (k$)

No. Users/Yr

Support (10 k$)

added part Bay 2

20+ Tesla Upgrade: Comparisons

Program Manager: Jian-Sheng Xia ………….U.F. Res. ScientistPostdoctoral Assoc: Liang Yin………………...NHMFL supported

Bay 2 Manager: Naoto Masuhara…............U.F. EngineerProgram assistant: Darlene Latimer…………U.F. StaffMicrokelvin Lab Director : Neil Sullivan ……….U.F. Faculty

Affiliated faculty (Physics):Gary Ihas

Yoonseok Lee Mark Meisel Neil Sullivan Yasu Takano Jian-sheng Xia

High-B/T Personnel

FINAL DESIGN