Quantum Matter Research under Extreme Physical

Conditions

Outlook for 2006-2007 in Korea

Kee Hoon KimSchool of Physics and Astronomy

& Center for Strongly Correlated Material Research

eXtreme Multifunctional Physics Laboratory (XMPL),

Seoul National University, South Korea

Sep. 27, 2006

Post-doc: Peter MannDeepshikha JaiswalRaj Sankar

Ph D candidates:Yoon Seok OhJae Wook KimSo-Young Haam

MS students:Sewhan Chun, Ingyu Kim

Peter Littlewood (Theory)

Christoph Bergemann (Exp.)

Peter Mann

S. S. Saxena

Stephen Rowley

G. G. Lonzarich

SNU (XMPL)

Kee Hoon Kim (Exp.)

Quantum Matter Group (Cavendish Lab.)

Quantum Criticality Proposed to Instigate New Phases Including Exotic Superconductivity

R. B. Laughlin et al., Adv. Phys. 50, 361 (2001).

AFM

AFI

Pseudogap

FL

FL

SC

SC

FL=res+AT2

1: fluctuations (e.g. spin fluctuations) present at T = 0 can mediate quasiparticle pairing

2: singular density of states (i.e. m* ) is unstable. Superconductivity very efficient at opening gap and lowering energy

Reasons:Non-Fermi Liquids

Fundamental questions:

can we understand new states of matter including exotic orders like high Tc superconductivity?

Quantum Matter Research AgendaQuantum Matter Research AgendaSNU (XMPL) Cavendish Quantum Matter

Group

Superconducting Bup to 21 T

Dilution Fridge5 mK

Anvil cell:150 kbar

Clamp cell:

30 kbar

Cavendish Correlated Electron Theory Group

P

B, T

Tools I: Quantum Matter Growth + Crystallography (x)

Optical Floating Zone Furnace +Flux Growth Technique

(Quantum) Multiferroics RMnO3…Highly frustrated quantum spin systemA new correlated Fermion system Pt cruciblePolarized

Microscope

Real time Laue analyses

GaFeO3 TbMn2O5

Tools II: Measurements under High Field up to 100 T (B)

All plastic and silicon; no eddy current !!

Phase-sensitive Synchronous Detection

Synchronous Clock (n x f )Dual Synthesizer

Digitizer

Drive ( f ) Signal

60 T calorimeter60 T calorimeter60 T calorimeter60 T calorimeter

100kHz ac tools100kHz ac tools100kHz ac tools100kHz ac tools

33 T 33 T NanocalorimeterNanocalorimeter

33 T 33 T NanocalorimeterNanocalorimeter

Outstanding problems to be answered

• How the phases can be formed near the QCP of a correlated matter? Is the new phase really linked to the QCP?

• A QCP can involve the large FS reconstruction? Fermiology vs Hall effects

K. H. Kim et al. PRL 93, 126404 (2004); K. H. Kim PRL 2003

Rh 4 %Rh 0 %

Research Highlight : Hall studies of U(Ru1-xRhx)2Si2

A jump in carrier number (n ~1 el/U) across phase II suggests the FS

reconstruction to induce a discontinuous Fermi surface volume

change.

Results of pulsed field explorations

dHv study at Cavendish lab. is most valuable to this problem

RH=xy/B=-1/ne

Y. S. Oh et al. submitted to PRL

Spin Orbital

Charge

MultifunctionalMultiferroic materials

Magnetic control

Electric control

Lattice/photonic control

H

P

M

E

P

,

M

Quantum Magnetism-Ferroelectricity Coupling in Multiferroics

GaFeO3 TbMn2O5

Next generation memory materials with more control ability

APSFocus Session

2003 년1

2004 년1

2005 년2

2006 년4

New material search+ highly senstive measurements tools:

2003-2006Nature 5Nature materials 6Science 7PRL 22

Very hot emerging research area

New multiferroics? ; Fundamental coupling mechanism?; Needs for multiphase space exp. ?

0 20 40 60 800

20

40

60

MA

GN

ET

IC F

IEL

D (

T)

TIME (msec)

electric polarizationdielectric constant

PE hysteresis loop

Magnetic birefringence

Magnetoelectric susceptibility

(film and low T study ready

0 5 10 15 20 25 300

10

20

30

40

T

(K

)

-186.0

-66.00

54.00

174.0

294.0

414.0

534.0

636.0P

E(nC/cm2)

B (T)

TbMn2O5

Multiferroic Xtals

S. Y. Haam et al., to submitted to PRL

Electric polarization map of a multiferroic under high magnetic fields

New high field phase transition

Quantum Paraelectric Matter

Understanding of electric polarization

generation

9T : PPMS

45T: mid-pulse 60T: short-pulse 100T: short-pulse

45T: static field

RMn2O5, RMnO3, RCrO3RMn2O5, RMnO3, RCrO3

Nano-Pillar CompositeNano-Pillar Composite

PZT:CoNi2Fe4PZT:CoNi2Fe4

Research Highlight : B-T phase diagram of multiferroics

ε(T) of BiMn2O5 at constant magnetic field

0 2 4 6 8 10 1236.0

36.5

37.0

37.5

38.0

38.5

39.0

18.11 T

18.07 T

18.14 T

18.04 T

BiMn2O

5

B//a Cooling

18.20 T

18.30 T

b

T (K)0 2 4 6 8 10 12

36.0

36.5

37.0

37.5

38.0

38.5

39.0

17.96 T

18.02 T18.04 T

17.90 T

BiMn2O

5

B//a Cooling

b

T (K)

Careful T sweep of dielectric constant near Bc down to 0.6 K

Very similar to the well-known quantum paraelectric behavior of SrTiO3

Can be a new quantum paraelectric achieved with magnetic field tuning?

J. W. Kim et al. to be submitted

A sign of quantum ferreoelectrics

Outstanding problems to be investigated

1. Can we find a new quantum paraelectrics near the quantum critical point of ferroelectrics or multiferroics? BiMn2O5 case

2. Can we realize new multiferroics ? (eg. SnTe doped with Mn?) Theory + Experiments (Design of materials)

3. Developments of quantum technology to explore challenging measurements Tiny magnetic moment measurement as tuned by electric fields Tiny specific heat measurements under quantum regime to see electronic quantum oscillations or to study phase transition at low T

Recently discovered superconducting below 50mK, Ag5Pb2O6 has a very simple Fermi surface with m*/m~1.

Sutherland et al, PRL 96, 097008 (2006)Mann et al, Physica C, M2S Proc. (2006)However, the resistivity is not simple. It has quasi-

T2 dependence up to at least room temperature. What is the cause? Phonons?

Yonezawa and Maeno, PRB 70, 184523 (2004)

It will be useful to measure C more precisely up to and beyond 400K using the high T heat capacity probe, to confirm saturation to Dulong-Petit value.

Plus we need more theory input…!

Peter Mann

Research plan, Ag5Pb2O6: a simple superconductor?

Research plan : Electric Field Induced Magnetic Moment

Electric field induced magnetization study

E-torque magnetometer developments and measurements for multiferroic thin film devices and crystals

E-VSM developments and study

Magnetoelectric susceptibility measurements for films at low temperatures

Study on new multiferroic materials and their nanostructure

Search for materials showing magnetic moment variation actuated by electric

fields

Developments of magnetoelectric device with naopillar and multilayer

forms

Ba-Hexaferrite, Y3Fe5O12, GaFeO3Ba-Hexaferrite, Y3Fe5O12, GaFeO3

Multiferroic crystal & film Fab. of highly senstive-measurement tool

Torque magnetometerTorque magnetometer

Ni3B7O12I

Switching of P (E~1000V/cm) by 180 deg. with a rotation of M (H~0.1 T) by 90 deg.

Z

x

y

P Ms

英 Cambridge Univ.

韓 SNU

1st year 2nd 3rd

Quantum Matter & Quantum Phase Transition

Quantum Matter Theory + High B & High B

Next generation measurement tools +

Search for a New groundstates of quantum matter

Understanding quantum criticality

and phase formation

Measurements under extreme limit

Quantum Matter Search, Growth, and Characterization

Pressure celldevelopment (4GPa)

Nano-calorimeter techniqueStriction cell fabrications

~10 mK ultralow temperatureHigh pressure measurements

Torquemagnetometer

Ultralow temp.(mK)calorimetry

Future Research StrategyFuture Research StrategyFuture Research StrategyFuture Research Strategy

NanocalorimetryQPT study

We’re looking forward to being part of the CKC family!We’re looking forward to being part of the CKC family!