scholarly journals Revealing hidden spin-momentum locking in a high-temperature cuprate superconductor

Science ◽  
2018 ◽  
Vol 362 (6420) ◽  
pp. 1271-1275 ◽  
Author(s):  
Kenneth Gotlieb ◽  
Chiu-Yun Lin ◽  
Maksym Serbyn ◽  
Wentao Zhang ◽  
Christopher L. Smallwood ◽  
...  
Keyword(s):  
High Temperature ◽  
Cuprate Superconductors ◽  
Photoemission Spectroscopy ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Spin Texture ◽  
High Temperature Cuprate Superconductor ◽  
Spin Momentum ◽  
Brillouin Zone Center

Cuprate superconductors have long been thought of as having strong electronic correlations but negligible spin-orbit coupling. Using spin- and angle-resolved photoemission spectroscopy, we discovered that one of the most studied cuprate superconductors, Bi2212, has a nontrivial spin texture with a spin-momentum locking that circles the Brillouin zone center and a spin-layer locking that allows states of opposite spin to be localized in different parts of the unit cell. Our findings pose challenges for the vast majority of models of cuprates, such as the Hubbard model and its variants, where spin-orbit interaction has been mostly neglected, and open the intriguing question of how the high-temperature superconducting state emerges in the presence of this nontrivial spin texture.

scholarly journals Phase shift in skyrmion crystals

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Satoru Hayami ◽  
Tsuyoshi Okubo ◽  
Yukitoshi Motome
Keyword(s):  
Phase Shift ◽  
Relative Phase ◽  
Exchange Interactions ◽  
Thermal Fluctuations ◽  
Coupled Systems ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Spin Density Waves ◽  
Vortex Crystal ◽  
Spin Texture

AbstractThe magnetic skyrmion crystal is a periodic array of a swirling topological spin texture. Since it is regarded as an interference pattern by multiple helical spin density waves, the texture changes with the relative phase shifts among the constituent waves. Although such a phase degree of freedom is relevant to not only magnetism but also transport properties, its effect has not been elucidated thus far. We here theoretically show that a phase shift in the skyrmion crystals leads to a tetra-axial vortex crystal and a meron-antimeron crystal, both of which show a staggered pattern of the scalar spin chirality and give rise to nonreciprocal transport phenomena without the spin-orbit coupling. We demonstrate that such a phase shift can be driven by exchange interactions between the localized spins, thermal fluctuations, and long-range chirality interactions in spin-charge coupled systems. Our results provide a further diversity of topological spin textures and open a new field of emergent electromagnetism by the phase shift engineering.

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.

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.

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