Kee Hoon Kim Quantum Matter Research under Extreme Physical Conditions

Sep. 27, 2006
Quantum Matter Research under Extreme Physical Conditions
Outlook for 2006-2007 in Korea
Kee Hoon Kim
School of Physics and Astronomy
& Center for Strongly Correlated Material Research
eXtreme Multifunctional Physics Laboratory (XMPL),
Seoul National University, South Korea
SNU (XMPL)
Kee Hoon Kim (Exp.)
Post-doc:
Peter Mann
Deepshikha Jaiswal
Raj Sankar
Quantum Matter Group
(Cavendish Lab.)
Peter Littlewood (Theory)
Christoph Bergemann (Exp.)
Peter Mann
S. S. Saxena
Ph D candidates:
Yoon Seok Oh
Jae Wook Kim
So-Young Haam
MS students:
Sewhan Chun, Ingyu Kim
Stephen Rowley
G. G. Lonzarich
Quantum Criticality Proposed to Instigate New Phases
Including Exotic Superconductivity
Non-Fermi Liquids
Reasons:
1: fluctuations (e.g. spin
fluctuations) present at
T = 0 can mediate
quasiparticle pairing
Pseudogap
FL
SC
AFI
2: singular density of
states (i.e. m*  ) is
unstable. Superconductivity
very efficient at opening gap
and lowering energy
Fundamental questions:
can we understand new states of matter
including exotic orders like high Tc
superconductivity?
rFL=rres+AT2
AFM
FL
SC
R. B. Laughlin et al., Adv. Phys. 50, 361 (2001).
Quantum Matter Research Agenda
SNU (XMPL)
Cavendish Quantum Matter Group
Clamp cell:
30 kbar
P
Anvil cell:
150 kbar
Cavendish Correlated Electron
Theory Group
Superconducting B
up to 21 T
Dilution Fridge
5 mK
B, T
Tools I: Quantum Matter Growth + Crystallography (x)
Optical Floating Zone Furnace +Flux Growth Technique
GaFeO3
(Quantum) Multiferroics RMnO3…
Highly frustrated quantum spin system
A new correlated Fermion system
TbMn2O5
crucible
PolarizedPt
Microscope
Real time Laue analyses
Tools II: Measurements under High Field up to 100 T (B)
60 Tesla CALORIMETER
60 T calorimeter
Heater
G-10 tube
33 T
Nanocalorimeter
Si platform
Sample
Thermometer
Cernox
resistive temperature sensor
Temperature
Regulated
Block
(2850 Stycast)
B-dot coil
approx. 3500 mm
100kHz ac tools
G-10 frame
All plastic and silicon; no eddy current !!
2
Synchronous Clock (n x f )
Dual Synthesizer
Digitizer
Drive ( f )
Phase-sensitive Synchronous Detection
Signal
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
Research Highlight : Hall studies of U(Ru1-xRhx)2Si2
Rh 0 %
Y. S. Oh et al. submitted to PRL
Rh 4 %
RH=rxy/B
=-1/ne
Results of
pulsed field
explorations
A jump in carrier number (n ~1 el/U) across phase II suggests the FS
reconstruction to induce a discontinuous Fermi surface volume change.
dHv study at Cavendish lab. is most valuable to this problem
Quantum Magnetism-Ferroelectricity Coupling in Multiferroics
GaFeO3
TbMn2O5
Charge
Multifunctional
Multiferroic materials
Spin
Very hot emerging
research area

P
Magnetic
control

M
New material search
+ highly senstive
measurements tools:
APS
Focus Session
2003년
1
Orbital

H
Electric
control
2004년
1
Lattice/photonic
control

P
M

E
Next generation
memory materials with
more control ability
2003-2006
Nature 5
Nature materials 6
Science 7
PRL 22

 ,
2005년
2
2006년
4
New multiferroics? ; Fundamental coupling mechanism?; Needs for multiphase space exp. ?
Research Highlight : B-T phase diagram of multiferroics
Electric polarization map of a multiferroic under high magnetic fields
S. Y. Haam et al., to submitted to PRL
534.0
30
T (K)
9T : PPMS
636.0
414.0
294.0
20
174.0
54.00
10
-66.00
MAGNETIC FIELD (T)
TbMn2O5
40
2
PE(nC/cm )
60
45T: static field
40
45T: mid-pulse
60T: short-pulse
100T: short-pulse
20
-186.0
0
0
5
10
15
20
25
0
30
B (T)
Multiferroic Xtals
0
20
40
TIME (msec)
60
80
Nano-Pillar Composite
RMn2O5, RMnO3, RCrO3
PZT:CoNi2Fe4
electric polarization
dielectric constant
PE hysteresis loop
Magnetic birefringence
Magnetoelectric susceptibility
(film and low T study ready
New high field phase transition
Quantum Paraelectric Matter
Understanding of electric polarization
generation
Careful T sweep of dielectric constant near Bc down to 0.6 K
J. W. Kim et al. to be submitted
39.0
39.0
BiMn2O5
38.5
38.0
B//a
Cooling
18.04 T
18.07 T
18.11 T
BiMn2O5
38.5
38.0
B//a
Cooling
18.04 T
18.02 T
18.14 T
b
b
ε(T) of BiMn2O5 at constant magnetic field
37.5
37.5 17.96 T
18.20 T
37.0 17.90 T
37.0
18.30 T
36.5
36.5
36.0
36.0
0
2
4
6
T (K)
8
10
12
0
2
A sign of quantum ferreoelectrics
4
6
8
T (K)
Very similar to the well-known quantum paraelectric behavior of SrTiO3
Can be a new quantum paraelectric achieved with magnetic field tuning?
10
12
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
Research plan, Ag5Pb2O6: a simple superconductor?
Peter Mann
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?
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…!
Yonezawa and Maeno, PRB 70, 184523 (2004)
Research plan : Electric Field Induced Magnetic Moment
Study on new multiferroic materials and their nanostructure
Multiferroic crystal & film
Ba-Hexaferrite, Y3Fe5O12, GaFeO3
Fab. of highly senstive-measurement tool
Torque magnetometer
Ni3B7O12I
Switching
of
P
(E~1000V/cm) by 180
deg. with a rotation of M
(H~0.1 T) by 90 deg.
Z
  
 
P
Ms
Search for materials showing magnetic
moment variation actuated by electric
fields
Developments of magnetoelectric device
with naopillar and multilayer forms

y
x
  
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
Future Research Strategy
韓 SNU
Quantum Matter Search, Growth, and Characterization
Nano-calorimeter technique
Striction cell fabrications
Pressure cell
development (4GPa)
Ultralow temp.(mK)
calorimetry
英 Cambridge Univ.
~10 mK ultralow temperature
High pressure measurements
Quantum Matter &
Quantum Phase Transition
Torque
magnetometer
Nanocalorimetry
QPT study
Next generation
measurement tools +
Search for a New
groundstates of quantum
matter
Understanding quantum
criticality and phase
formation
Measurements under
extreme limit
Quantum Matter Theory + High B & High B
1st year
2nd
3rd
We’re looking forward to being part of the CKC family!