1 A. A. Katanin a,b,c and A. P. Kampf c 2004 a Max-Planck Institut für Festkörperforschung, Stuttgart b Institute of Metal Physics, Ekaterinburg, Russia.
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1
A. A. Katanina,b,c and A. P. Kampfc
2004
a Max-Planck Institut für Festkörperforschung, Stuttgartb Institute of Metal Physics, Ekaterinburg, Russiac Theoretische Physik III, Institut für Physik, Universität Augsburg
Anomalous self-energy and pseudogap formation near
an antiferromagnetic instability
2
IntroductionIntroduction
PM (Fermi liquid,
well-defined QP)
metallic AF (n 1)
T*0
PM
metallic AF
T*
C exp(T*/T),T < T*
C exp(T*/T),T < T*
T
dSC
T
2-ndorder QPT
1-storder QPT
Previous studies:SF model (A. Abanov, A. Chubukov, and J. Schmalian)2D Hubbard model:• DCA (Th. Maier, Th. Pruschke, and M. Jarrell)• FLEX (J. J. Deisz et al., A. P. Kampf) • TPSC (B. Kyung and A. M.-S. Tremblay)
• What are the changes in the electronic spectrum on approaching an AF metallic phase in 2D ?
RC
RC
3
Cuprates: experimental resultsCuprates: experimental results
Pseudogap regime – the spectral weight at the Fermi levelis suppressed.
SC
AFM PG
Partly “metallic” behavior even at very low hole doping
From:T. Yoshida et al., Phys. Rev. Lett. 91, 027001 (2003).
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0.01.00.0
0.5
The model and AF orderThe model and AF ordert'/t
AF order at large U in a nearly half-filled band – AF Mott insulator AF order due to peculiarities of band structure – Slater antiferromagnetism:
n
-2 0 2 4
t
0.1
0.3
0.5
()
iii nnUccH
,kkkk
0',)1coscos('4)coscos(2 tkktkkt yxyx k
The model:
van Hove band fillings
• C. J. Halboth and W. MetznerPhys. Rev. B 61, 7364 (2000)• C. Honerkamp, et al., Phys. Rev. B 63, 035109 (2001)
1n
• Two possibilities to have AF order:
1.01.00.00.0
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Self-energy: mean-field resultsSelf-energy: mean-field results
Im i
Re
k+Q 0
Im
Re
k+Q
k+Q 0
iQk
2)(
A
B
A
B
A
B
nnvH
nnvH
Q
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The functional RGThe functional RG
=
.
.
.
.=
0
]***['* '''' VGSVdS
V* )G*SS*(G *V V
Discretization of themomentum dependenceof the interaction
k
k
k
k
nn iS
iG
)|(|;
)|(|
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Self-energy at vH band fillingsSelf-energy at vH band fillings
Spectral properties are strongly anisotropic around the Fermi surface
The quasiparticle concept is violated at kF=(,0) and valid in a narrow window around for other kF
The spectral properties are mean-field like for k=(,0) while they are qualitatively different from MF results for other kF
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Self-energy near vH band fillingsSelf-energy near vH band fillings
Unlike vH band fillings, magnetic fluctuations suppress spectral weight, but are not sufficient to drop spectral weight to zero.
The quasiparticle concept is valid in a narrow window around for all kF
Similiarity with thePM – PI, U < Uc
Hubbard sub-bands
Mott-Hubbard DMFT picture
Quasiparticle peak, Z0
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ConclusionsConclusions
The spectral weight is anisotropic around FS and decreases towards (,0).
At the (,0) point two-peak pseudogap structure of the spectral function arises.
At the other points the spectral function has three-peak form
Weak U
Strong U
(,0) (,)
(,0) (,)
Spectral weight transfer Spectral weight transfer
Hubbard sub-bands
Magnetic sub-bands
Possible scenario for strong coupling regime in the nearly half-filled 2D Hubbard model
Quasiparticle peak
Therefore, at finite t' and away from half filling
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