band structure of strongly correlated materials from the dynamical mean field perspective
DESCRIPTION
K Haule Rutgers University Collaborators : J.H. Shim & Gabriel Kotliar. Band structure of strongly correlated materials from the Dynamical Mean Field perspective. Fe, Ni. As, P. La,Sm,Ce. O. Iron based high-Tc superconductors. x~5-20%. Smaller c Higher T c. - PowerPoint PPT PresentationTRANSCRIPT
Urbana-Champaign, 2008
Band structure of strongly correlated materials from the Dynamical Mean Field perspective
K HauleRutgers University
Collaborators : J.H. Shim & Gabriel Kotliar
LaOFeP 3.2K, JACS-2006
a=3.964A, c=8.512A
PrFxO1-xFeAs d) 52K, unpublished
a=3.985A, c=8.595A
SmFxO1-xFeAs c) 43K, cm/0803.3603
a=3.940A, c=8.496A
CeFxO1-xFeAs b) 41 K, cm/0803.3790
a=3.996A, c=8.648A
LaFxO1-xFeAs a) 26 K, JACS-2008
a=4.036A, c=8.739 A
La1-xSrxOFeAs 25K, cm/0803.3021,
a=4.035A, c = 8.771A
LaCaxO1+xFeAs 0 K
LaFxO1-xNiAs 2.75K, cm/0803.2572a=4.119A , c=8.180A
La1-xSrxONiAs 3.7K, cm/0803.3978
a=4.045A, c=8.747A
x~5-20%
Fe,Ni
As,P
La,Sm,Ce
O
•2D square lattice of Fe•Fe - magnetic moment•As-plays the role of O in cuprates
Sm
aller
cH
igh
er
Tc
Iron based high-Tc superconductors
a) Y. Kamihara et.al., Tokyo, JACSb) X.H. Chen, et.al., Beijing, cm/0803.3790c) G.F. Chen et.al., Beijing, cm/0803.3603d) Z.A. Ren et.al, Beijing, unpublished
Y. Kamihara et.al., J. Am. Chem. Soc. XXXX, XXX (2008)
A.S. Sefat. et.al., cond-mat/0803.2403
Specific heat consistent with nodes! Possibly d wave..
Kink in resistivitymaybe SDW
LaFxO1-xFeAs
Y. Kamihara, J. Am. Chem. Soc. XXXX, XXX (2008)
Undoped compound:•Huge resistivity
Doped compound:•Large resistivity >> opt. dop. Cuprates
•Huge spin susceptibility( >> 100 bigger than in
LSCO50 x Pauli)
•Spin susceptibility of an almost free spins
~C/(T+120K) with C of S~1
Wilson’s ratioR~1 F0
a small
LaFxO1-xFeAs
LDA: phonons-Tc<1K
KH, J.H. Shim, G. Kotliar, cond/mat 0803.1279
LDA: Mostly iron bands at EF (correlations important)
LDA DOS
6 electrons in 5 Fe bands:Filling 6/10
LDA for LaOFeAs
x2-y2
yz, xz
z2
xy 60meV
160meV
60meV
LDA+DMFT: LaOFeAs is at the verge of the metal-insulator transition (for realistic U=4eV, J=0.7eV)For a larger (U=4.5, J=0.7eV) Slater insulator
Not a one band model: all 5 bands important (for J>0.3)
DMFT for LaFxO1-xFeAs
Need to create a singlet out of spin and orbit
In LaOFeAs semiconducting gap is openingLarge scattering rate at 116K
Optical conductivity of a bad metal
No Drude peak
Electron pockets around M and A upon doping
DMFT for LaFxO1-xFeAs
T=116 K
10% doping