scholarly journals Observation of small Fermi pockets protected by clean CuO2 sheets of a high-Tc superconductor

Science ◽  
2020 ◽  
Vol 369 (6505) ◽  
pp. 833-838 ◽  
Author(s):  
So Kunisada ◽  
Shunsuke Isono ◽  
Yoshimitsu Kohama ◽  
Shiro Sakai ◽  
Cédric Bareille ◽  
...  
Keyword(s):  
Cuprate Superconductors ◽  
Parent Compound ◽  
High Critical Transition Temperature ◽  
Photoemission Spectroscopy ◽  
Hole Doping ◽  
Quantum Oscillation ◽  
Critical Transition Temperature ◽  
High Tc ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Antiferromagnetic Ordering

In cuprate superconductors with high critical transition temperature (Tc), light hole-doping to the parent compound, which is an antiferromagnetic Mott insulator, has been predicted to lead to the formation of small Fermi pockets. These pockets, however, have not been observed. Here, we investigate the electronic structure of the five-layered Ba2Ca4Cu5O10(F,O)2, which has inner copper oxide (CuO2) planes with extremely low disorder, and find small Fermi pockets centered at (π/2, π/2) of the Brillouin zone by angle-resolved photoemission spectroscopy and quantum oscillation measurements. The d-wave superconducting gap opens along the pocket, revealing the coexistence between superconductivity and antiferromagnetic ordering in the same CuO2 sheet. These data further indicate that superconductivity can occur without contribution from the antinodal region around (π, 0), which is shared by other competing excitations.

scholarly journals Fermi surface in La-based cuprate superconductors from Compton scattering imaging

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hiroyuki Yamase ◽  
Yoshiharu Sakurai ◽  
Masaki Fujita ◽  
Shuichi Wakimoto ◽  
Kazuyoshi Yamada
Keyword(s):  
Distribution Function ◽  
Fermi Surface ◽  
Compton Scattering ◽  
Momentum Distribution ◽  
Cuprate Superconductors ◽  
Photoemission Spectroscopy ◽  
Quantum Oscillation ◽  
Strong Temperature Dependence ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Momentum Distribution Function

AbstractCompton scattering provides invaluable information on the underlying Fermi surface (FS) and is a powerful tool complementary to angle-resolved photoemission spectroscopy and quantum oscillation measurements. Here we perform high-resolution Compton scattering measurements for La2−xSrxCuO4 with x = 0.08 (Tc = 20 K) at 300 K and 150 K, and image the momentum distribution function in the two-dimensional Brillouin zone. We find that the observed images cannot be reconciled with the conventional hole-like FS believed so far. Instead, our data imply that the FS is strongly deformed by the underlying nematicity in each CuO2 plane, but the bulk FSs recover the fourfold symmetry. We also find an unusually strong temperature dependence of the momentum distribution function, which may originate from the pseudogap formation in the presence of the reconstructed FSs due to the underlying nematicity. Additional measurements for x = 0.15 and 0.30 at 300 K suggest similar FS deformation with weaker nematicity, which nearly vanishes at x = 0.30.

PHOTOEMISSION STUDY OF THE INTRA-UNIT-CELL COUPLING IN A TRILAYER CUPRATE

2002 ◽  
Vol 16 (11n12) ◽  
pp. 1691-1696 ◽  
Author(s):  
D. L. FENG ◽  
H. EISAKI ◽  
K. M. SHEN ◽  
A. DAMASCELLI ◽  
C. KIM ◽  
...  
Keyword(s):  
Electronic Structures ◽  
Cuprate Superconductors ◽  
Single Layer ◽  
Interlayer Coupling ◽  
Unit Cell ◽  
Photoemission Spectroscopy ◽  
Cell Coupling ◽  
Lineshape Analysis ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Photoemission Study

The electronic structures of the nearly optimally doped single-layer, bilayer and trilayer Bi-based cuprates are investigated by angle-resolved photoemission spectroscopy. A lineshape analysis of data taken for different photon energies indicates that the interlayer coupling within the trilayer is not stronger than its counterpart in the bilayer system. This suggests that the higher T c of the trilayer cuprate superconductors is not due to an enhancement of the coupling strength between the neighboring CuO2 planes within each unit cell.

High Resolution Photoelectron Study of the Optimum Oxygen Doping Levels in High Tc Superconductors

1993 ◽  
Vol 307 ◽  
Author(s):  
R. J. Kelley ◽  
X. C. Cai ◽  
Jian Ma ◽  
D. C. Larbalestier ◽  
M. Onellion
Keyword(s):  
High Resolution ◽  
Electronic Properties ◽  
Cuprate Superconductors ◽  
Underlying Mechanism ◽  
Oxygen Stoichiometry ◽  
Photoemission Spectroscopy ◽  
Standard Material ◽  
Resonant Photoemission ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Photoelectron Study

ABSTRACTThe materials and electronic properties of the new cuprate superconductors are critically dependent upon both the oxygen stoichiometry and annealing history of the material. Improving Jc, Tc, and determining the underlying mechanism of superconductivity depend on a better understanding of these effects. In the study of Bi2Sr2CaCu2O8-δ we have combined standard material characterization techniques with high resolution angle resolved photoemission spectroscopy and resonant photoemission spectroscopy to illuminate these issues. Specifically, we make high quality single crystals of BSCCO and then anneal in different atmospheres and pressures. We correlate this with c-axis resistivity, a, b-plane resistivity, and resonant photoemission spectroscopy. In this way we can explain the macroscopic transport properties in terms of the electronic properties of the material determined from photoemission. We find that we can change the c-axis resistivity from non-metallic to metallic by adding oxygen and that this correlates with increased oscillator strength in the c-axis direction at the Fermi level.

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