Electron Materials : A Electron Materials : A Dynamical Mean Field Dynamical Mean Field Theory (DMFT) Perspective. Theory (DMFT) Perspective. Gabriel Kotliar Gabriel Kotliar and Center for Materials Theory $upport : NSF -DMR DOE-Basic Energy Sciences Cornell Ithaca NY November 27 2007 Cornell Ithaca NY November 27 2007 1 1
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Strongly Correlated Electron Materials Strongly Correlated Electron Materials : A Dynamical Mean Field Theory : A Dynamical Mean Field Theory
(DMFT) Perspective.(DMFT) Perspective. Gabriel KotliarGabriel Kotliar
and Center for Materials Theory
$upport : NSF -DMR DOE-Basic Energy Sciences
Cornell Ithaca NY November 27 2007Cornell Ithaca NY November 27 2007
11
Outline Outline
• Introduction to strongly correlated materials.
• Brief overview of Dynamical Mean Field Theory.
• Application to heavy fermions: a case study of CeIrIn5 [with K. Haule and J. Shim, Science Express Nov 1st (2007) ]
• Conclusions – and some thought about the 5f elemental metals.
.Interactions renormalize away (Landau) . Band Theory: electrons as waves
Electrons in a Solid:the Standard Model Electrons in a Solid:the Standard Model
•Quantitative Tools. Density Functional Theory Kohn Sham
Kohn Sham Eigenvalues and Eigensates: Excellent starting point for perturbation theory in the screened interactions (Hedin 1965)
Self Energy Self Energy
M VanShilfgaarde et. al. PRL M VanShilfgaarde et. al. PRL 9696, , 226402 (2006)226402 (2006)
33
Correlated Electron Systems Pose Basic Correlated Electron Systems Pose Basic Questions in CMTQuestions in CMT
• FROM ATOMS TO SOLIDS
• How to describe electron from localized to itinerant ?
• How do the physical properties evolve ?
Strong Correlation Problem:where Strong Correlation Problem:where the standard model failsthe standard model fails
• Fermi Liquid Theory works but parameters can’t be computed in perturbative theory.
• Fermi Liquid Theory does NOT work . Need new concepts to replace of rigid bands !
• Partially filled d and f shells. Competition between kinetic and Coulomb interactions.
• Breakdown of the wave picture. Need to incorporate a real space perspective (Mott).
• Non perturbative problem.
44
Strongly correlated materials do “big” thingsStrongly correlated materials do “big” things
• Huge volume collapses Pu …….• Masses as large as 1000 me
(heavy fermions UPt3, CeIrIn5…..
• High Temperature Superconductivity. 150 K Ca2Ba2Cu3HgO8 .• Large thermoelectric response in NaxCo2O4
• Large change in resistivity. MIT in TM oxides (V2O3, VO2, LaSrMnO3……..)
• …………………..55
Hubbard model Hubbard model
† †
, ,
( )( )ij ij i j j i i ii j i
t c c c c U n n
U/t
Doping or chemical potential
Frustration tij
T temperature
66
†i i ic c n
Mott-Hubbard PhysicsMott-Hubbard PhysicsBaBa
Real space picture
High T : local moments
Low T: spin orbital order
1
T
HH HH HH HHHH++
Excitations: Excitations: Excitations: adding (removing ) e, Upper Hubbard
band.
77
Dynamical Mean Field Theory. Cavity Construction.Dynamical Mean Field Theory. Cavity Construction. A. Georges and G. Kotliar PRB 45, 6479 (1992).A. Georges and G. Kotliar PRB 45, 6479 (1992).
†
0 0 0
( )[ ( ' ] ( '))o o o oc c U n nb b b
s st m tt
t t ¯
¶+ D-
¶- +òò ò
,ij i j i
i j i
J S S h S- -å å eMF offhH S=-† †
, ,
( )( )ij ij i j j i i ii j i
t c c c c U n n
*
( )V Va a
a a
ww e
D =-å
† † † † †Anderson Imp 0 0 0 0 0 0 0
, , ,
( +c.c). H c A A A c c UcV c c c
A(A())
1010
A. Georges, G. Kotliar (1992)
( )wDlatt ( ,
1 G [ ]
( ) [( ) ])
[ ]n impn
n
ik ii
ktw m
ww+ + - S
DD
=
latt( ) G ([ [)] ] ,imp n nk
G i i kw wD D=å
[ ]ijij
jm mJth hb= +å
11
( ( )( )
( [))
][ ]
imp n
imp n
kn
G i
Gti
ik
w
ww -D
D
=+-
å
A(A())
1111
Dynamical Mean Field TheoryDynamical Mean Field Theory
• Weiss field is a function. Multiple scales in strongly correlated materials.
• Exact in the limit of large coordination (Metzner and Vollhardt 89) , kinetic and interaction energy compete on equal footing.
• Immediate extension to real materials
, ,
, 22
[ ] [ ]( )
[ ] [ ]spd sps spd f
f spd ff
H k H kt k
H k H k
æ ö÷ç ÷ç ÷ç ÷çè ø®
| 0 ,| , | , | | ... JLSJM g> > ¯> ¯> >®
DFT+DMFTDFT+DMFT1212
DMFT Spectral Function Photoemission and DMFT Spectral Function Photoemission and correlationscorrelations
• Probability of removing an electron and transfering energy =Ei-Ef, and momentum k
f() A() M2
e
Angle integrated spectral Angle integrated spectral function function
( , ) ( )dkA k A 88
Evolution of the DOS. Theory and experimentsEvolution of the DOS. Theory and experiments
( )A 1313
, '( )RL RLA
Summary: DMFTSummary: DMFTSelf consistent Impurity problem, natural language to quantify localization/delocalization phenomena.
•Larger gap due to hybridization with out of plane In•Smaller gap due to hybridization with in-plane In
non-fspectra
T=10K T=300Kscatteringrate~100meV
Fingerprintofspd’sduetohybridization
Notmuchweight
q.p. bandSO
DMFT-MomentumresolvedCe-4fspectra
Af(,k)
Hybridizationgap
DMFTqpbands
LDAbands LDAbands DMFTqpbands
Quasiparticlebands
threebands,Zj=5/2~1/200
Quantum Phase Transition: Kondo Quantum Phase Transition: Kondo Breakdown vs SDW. Breakdown vs SDW.
• SDW picture. Focus on order parameters. Neglect changes in the electronic structure.[Hertz, Morya]
• Kondo breakdown scenario. Drastic changes in the electronic structure. [Doniach] [ Coleman, Pepin, Paul, Senthil, Sachdev, Vojta, Si ]
3
2. mod 2(2 )
FSc f
Vn n
p= +
V> VcV> Vc
3
2. mod 2(2 )
FSc
Vn
p=
Neglect Magnetic orderNeglect Magnetic order
V < Vc V < Vc c
3mod 1= n
(2 )FS
c fV
n np
= +Magnetic OrderMagnetic Order
.
DMFT: consider the underlying DMFT: consider the underlying paramagnetic solution. Study finite T. paramagnetic solution. Study finite T.
Kondo Breakdown as an Orbitally selective Mott Kondo Breakdown as an Orbitally selective Mott Transition. [L. DeMedici, A. Georges GK and S. Transition. [L. DeMedici, A. Georges GK and S. Biermann PRL (2005), C. Pepin (2006) , L. DeLeo Biermann PRL (2005), C. Pepin (2006) , L. DeLeo M. Civelli and GK ]M. Civelli and GK ]
• Analogous situation to the Mott transition. Mott / Slater.
• f localization - Jump in the Fermi volume-Jump in DeHaas VanAlven frequencies.
• f Localized and f Itinerant phases have different compressibilities.
• Low but finite temperature aspects of the transition governed by a two impurity model.
Fermi surface changes under Fermi surface changes under pressure in CeRhInpressure in CeRhIn55
– Fermi surface reconstruction at 2.34GPa . Sudden jump of dHva frequencies
– Delocalization. Increase of electron FS frequencies . Localization decreases them.
• Long wavelength vs short distance [ mean field ] physics in correlated materials.
• Further improvements and developments of DMFT [ CDMFT, electronic structure]
• Other systems. […..] System specific studies. Variety and universality in the localization delocalization phenomena.
• Towards a (Dynamical ) Mean Field Theory based theoretical spectroscopy.
Conclusions [115’s]Conclusions [115’s]
• DMFT in action: collective behavior of the hybridization field. Very slow crossover. Spectral evolution. Valence histograms.
• Theory/Experiment Spectroscopy. Multiple hybridization gaps in optics.
• Very different Ce-In hybridizations with In out of plane being larger.• Kondo breakdown as an orbitally selective
Mott transition. dhv orbits. • Lessons for the 5f’s. Elemental actinides.
Thanks!Thanks!
• $upport NSF-DMR.
• Collaborators: K. Haule, L. DeLeo, J. Shim, M. Civelli.
K. Haule and J. Shim and GK, Science Express Nov 1st (2007). To appear in science.
after G. Lander, Science (2003)and Lashley et. al. PRB (2006).
Mott Transition
PuPu
Mott transition across the actinides. B. Johansson Phil Mag. 30,469 (1974)]
DMFT Qualitative Phase diagram of a DMFT Qualitative Phase diagram of a frustrated Hubbard model at integer fillingfrustrated Hubbard model at integer filling
• Modern understanding (DMFT) of the (orbitally selective) Mott transition across the actinde series (B. Johanssen 1970 ) sheds light on 5f physics.
• Important role of multiplets. Pu is non magnetic and mixed valent element mixture of f6 and f5
• f electrons are localized in Cm f7 • Physics of 5f’s and 4f’s is similar but different. Main
difference, the coherence scale in 5f’s much larger, resulting in a much larger coupling to the lattice.
K. Haule and J. Shim Ref: Nature 446, 513, (2007)
Pu phases: A. Lawson Los Alamos Science 26, (2000) Pu phases: A. Lawson Los Alamos Science 26, (2000)
GGA LSDA predicts Pu to be magnetic with a large moment ( ~5 Bohr) . Experimentally Pu is not magnetic. [PRB 054416(2005). Valence of Pu is controversial.
DMFTPhononsinfccDMFTPhononsinfcc-Pu-Pu
C11 (GPa) C44 (GPa) C12 (GPa) C'(GPa)
Theory 34.56 33.03 26.81 3.88
Experiment 36.28 33.59 26.73 4.78
( Dai, Savrasov, Kotliar,Ledbetter, Migliori, Abrahams, Science, 9 May 2003)
(experiments from Wong et.al, Science, 22 August 2003)
Two Site Cellular DMFTTwo Site Cellular DMFT (G.. Kotliar et.al. PRL (2001)) in the 1D in the 1D Hubbard modelHubbard model M.Capone M.Civelli V. Kancharla C.Castellani and GK PRB
69,195105 (2004)T. D Stanescu and GK PRB (2006)
2424
High Temperature superconductorsHigh Temperature superconductors
LeTacon et.al. Nature Physics (2006)
Raman Hg-1201
2626
Doping Driven Mott transiton at low temperature, in 2d Doping Driven Mott transiton at low temperature, in 2d ((U=16 t=1, t’=-.3U=16 t=1, t’=-.3 ) Hubbard model ) Hubbard model
Spectral Function A(k,Spectral Function A(k,ω→ω→0)= -1/0)= -1/ππ G(k, G(k, ωω →→0) vs k0) vs k
K.M. Shen et.al. 2004
2X2 CDMFT
Nodal Region
Antinodal Region
Civelli et.al. PRL 95 (2005)Civelli et.al. PRL 95 (2005)
Conclusion Conclusion
• DMFT conceptual framework to think about electrons in solids.
• Finite T Mott transition in 3d . Single site DMFT worked well!
• Ab-initio many body electronic structure of solids. Building theoretical spectroscopies.
• Frontier, cuprates, lower T, two dimensionality is a plaquette in a medium enough?
• Inhomogenous structure in correlated materials• New renormalizaton group methods built around
DMFT ?2828
Conclusion Conclusion
• A Few References ……
• A.Georges, G. K., W. Krauth and M. J. Rozenberg, Reviews of . Modern Physics 68, 13 (1996).
• G. K, S. Y. Savrasov, K. Haule, V. S. Oudovenko, O. Parcollet, C.A. Marianetti, RMP 78, 865-951, (2006).
• G. K and D. Vollhardt Physics Today, Vol 57, 53 (2004).
2929
OutlineOutline
• The standard model of solids.
• Correlated electrons and Dynamical Mean Field Theory (DMFT).
• The temperature driven Mott transition.
• Mott transition across the actinide series.
• Future Directions, cuprate superconductors and Cluster DMFT……
+ KS crystalV V 10KSG 1G
Kohn Sham Eigenvalues and Eigensates: Excellent starting point for perturbation theory in the screened interactions (Hedin 1965)
Self Energy Self Energy
VanShilfgaarde (2005)VanShilfgaarde (2005)
Kohn Sham Eigenvalues and Eigensates: Excellent starting point for perturbation theory in the screened interactions (Hedin 1965)
High Temperature superconductorsHigh Temperature superconductors
Mott transition: Mott transition: evolution of the electron from itinerant to localized ? How
Matsuura et. al.Matsuura et. al.(2000)(2000)
-(BEDT-TTF)2Cu[N(CN)2]Cl LLefevre et.al.
(2000)Limelette et al.,(2003)Kagawa et al. (2003) 99
Interaction with Experiments. Photoemission Three Interaction with Experiments. Photoemission Three peak strucure. peak strucure. V2O3:Anomalous transfer of spectral V2O3:Anomalous transfer of spectral
weightweight
M. Rozenberg G. Kotliar H. Kajueter G Thomas D. Rapkine J Honig and P
Metcalf Phys. Rev. Lett. 75, 105 (1995)
T=170T=170
T=300T=300
1515
. Photoemission measurements and TheoryPhotoemission measurements and TheoryV2O3 V2O3 Mo, Denlinger, Kim, Park, Allen, Sekiyama, Yamasaki, Mo, Denlinger, Kim, Park, Allen, Sekiyama, Yamasaki, Kadono, Suga, Saitoh, Muro, Metcalf, Keller, Held, Eyert, Anisimov, Kadono, Suga, Saitoh, Muro, Metcalf, Keller, Held, Eyert, Anisimov,
Vollhardt PRL . (2003Vollhardt PRL . (2003))NiSxSeNiSxSe1-x1-xMatsuura Watanabe Kim Doniach Shen Thio Bennett (1998)Matsuura Watanabe Kim Doniach Shen Thio Bennett (1998)
Poteryaev et.al. (to be published)Poteryaev et.al. (to be published)1616
Spinodals and Ising critical endpoint. Spinodals and Ising critical endpoint. Observation in VObservation in V22OO3 3 :: P. Limelette et.al. Science 302, 89 (2003)P. Limelette et.al. Science 302, 89 (2003)
Critical endpoint Critical endpoint
Spinodal Uc2Spinodal Uc2
1717
Spectral Function and PhotoemissionSpectral Function and Photoemission
• Probability of removing an electron and transfering energy =Ei-Ef, and momentum k
f() A() M2
e
Angle integrated spectral Angle integrated spectral function function
( , ) ( )dkA k A 88
Georges Kotliar (1992)Georges Kotliar (1992)
DDMFT approximate quantum solid as atom in a mediumMFT approximate quantum solid as atom in a medium † †
, ,
( )( )ij ij i j j i i ii j i
t c c c c U n n
† † † † †Anderson Imp 0 0 0 0 0 0 0
, , ,
( +c.c). H c A A A c c UcV c c c
1010
, ,
,
[ ] [ ]( )
[ ] [ ]spd sps spd f
f spd ff
H k H kt k
H k H k
æ ö÷ç ÷ç ÷ç ÷çè ø®
| 0 ,| , | , | | ... JLSJM g> > ¯> ¯> >®
(GW) DFT+DMFT: determine H[k] and density and(GW) DFT+DMFT: determine H[k] and density andself consitently from a functionalself consitently from a functional
and obtain total energies. and obtain total energies. 1212
[ ]*
11
( )( ) (
,)n n
n nk
i ii t k i
V VVa a
aaaa
ew m ww m ww e
-é ùê ú+ - = +Sê ú+ - - S- ë û
å å
1( , )
( ) ( )G k i
i t k i
Spectra=- Im G(k,)
Self consistency for V and
Chitra and Kotliar Chitra and Kotliar PRB 62, 12715 (2000) PRB (2001)P.Sun and GK (2005) Zein PRB 62, 12715 (2000) PRB (2001)P.Sun and GK (2005) Zein
et.al.et.al. PRL PRL 96, 96, 226403 (2006)). See also Bierman Aryasetiwan and Georges. 226403 (2006)). See also Bierman Aryasetiwan and Georges.
Ir,>=|R, > Gloc=G(R, R’ ’ ) R,R’
1
2
1
1 ( ) Hartreecryst
Coulomb
VG i V
W
r
V P
Introduce Notion of Local Greens functions, Wloc, Gloc G=Gloc+Gnonloc .
[ , ] [ , , 0, 0]DMFT loc loc nonloc nonlocG W G W G W
Electronic structure problem: compute <r|G|r’> and <r|W|r’> given structure