Workshop on Strongly Correlated Systems, Seoul National University, October Photoemission spectrosco

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Spectroscopies in Novel Superconductors, July
11-16, 2004, Sitges, Spain
Pseudogap and Fermi arc in lightly-doped cuprates
A. Fujimori University of Tokyo
T. Yoshida (U. Tokyo) X.-J. Zhou, Z.-X. Shen
(Stanford U.) Z. Hussain (ALS) T. Kakeshita, S.
Uchida (U. Tokyo) H. Eisaki (AIST) Y. Ando, A.N.
Lavrov, K. Segawa (CRIEPI) Discussion Y.
Yanase, H. Fukuyama
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Outline

• Pseudogap and Fermi arc
• Electronic specific heats
• DC transport
• Conclusion

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Phase diagram, Fermi surface and d-wave order
parameter in high-TC cuprates
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Pseudogap behavior to Fermi arc in La2-xSrxCuO4
EDC
Intensity (abs. units)
Energy relative to EF (eV)
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Spectral weight of nodal quasi-particle
spectral weight of nodal QP z ? x

T. Yoshida et al., PRL 03
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Doping-independent nodal Fermi velocity
X.J. Zhou et al.,Nature 03
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Band dispersion in lightly-doped region
Antinode
Node
MDC
MDC
T. Yoshida et al., PRL 03
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Fermi surface, remnant Fermi surface
Tight binding model E(k) -2t(cos kxacos
kya) - 4tcos kxa cos kya -
2t(cos2kxacos2kya) E 0
TB fit
MDC peak
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Luttinger sum rule
Experimental and fitted band structure and Fermi
surface
x
TB fit
MDC peak
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Pseudogap in the anti-nodal region
Tight binding fit
MDC peak
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Identification of QP peak along the (remnant)
Fermi surface
x0.03
X.J. Zhou et al.,PRL 04
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Fermi arc in lightly-doped YBa2Cu3Oy (d0.04)
YBa2Cu3Oy (d0.04)
La2-xSrxCuO4 (x0.03)
H. Yagi et al.
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Outline

• Pseudogap and Fermi arc
• Electronic specific heats
• DC transport
• Conclusion

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Pseudogap behaviors in La2-xSrxCuO4
Y.J. Uemura et al., PRL 89
H. Takagi et al., PRB 89
T. Nakano et al., PRB 94
N. Momono et al., JPSJ 03
Hole doping x
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Band structure and Fermi surface
Experimental and fitted band structure and Fermi
surface
x
TB fit
MDC peak
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Band structure and QP density at the Fermi level
DOS of the tight-binding band
DOS ( QP density) at EF
DOS
N. Momono et al., Physica C 94
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Outline

• Pseudogap and Fermi arc
• Electronic specific heats
• DC transport
• Conclusion

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Unusual metallic transport in lightly-doped
cuprates
Y. Ando et al. PRL 01
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Band dispersion in lightly-doped region
Antinode
Node
MDC
MDC
T. Yoshida et al., PRL 03
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Doping and momentum dependence of Dk
Mean free path l 1/Dk
Dk
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Boltzmann transport
ky
E
kF
(p,p)
q
kx
Explains only a factor of 2 increase in
resistivity with underdoping cf) transport
expt gt102
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Boltzmann transport on the Fermi arc
Boltzmann transport on the Fermi arc
Entire Fermi surface
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Origin of the pseudogap and Fermi arc ?
d-wave-like pseudogap of RVB origin ? -
antinodal gap in A(k,w) H. Fukuyama - vF
constant, z x M. Randeria, R. B.
Laughlin - compatible with 4x4 charge ordring
P.W. Anderson
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Origin of the pseudogap and Fermi arc ?
(Pseudo)gap due to AF fluctuations ? J. R.
Schieffer , P. Prelovsek, K. Yamada Charge
ordering ? D. H. Lee
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Summary

• Pseudogap and Fermi arc are characterized by
  ARPES in detail, particularly for LSCO.
• Fermi surface and remnant Fermi surface satisfy
  the Luttinger sum rule.
• Sharp peak exists only on the arc.
• Electronic specific heat
• Suggests that most of QPs disappear from EF in
  the anti-nodal region.
• DC transport
• Conventional Boltzmann transport fails to explain
  the resistivity increase for x ? 0 and the
  violation of the Ioffe-Regel limit.
• Disappearance of QPs in the anti-nodal region
  reduces the dc conductivity.

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Doping and momentum dependence of vF