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