Angle-Resolved Photoemission Studies on the Many-Body Effects of High-Temperature Superconductor: Bi-2212

Spin fluctuations are defined as dynamic variations of spin density in both space and time. They are widely considered to play a essential role in the pairing mechanism of high temperature superconductors. Unconventional superconductors such as cuprates are believed to exhibit spin-fluctuation-mediated pairing, as opposed to conventional superconductors where phonons mediate Cooper pairing. Dynamic spin susceptibility can characterize these fluctuations. It describes the magnetic response of the system to perturbations. The imaginary part of this function captures the full spectrum of spin excitations in both the normal and superconducting states. It can be typically measured via inelastic neutron scattering (INS). However, such measurements for Bi-2212 are rare because of small scattering cross-sections and difficulties in growing sufficiently large crystals. In this work, we developed a stable photon-energy helium lamp–based ARPES (angle-resolved photoemission spectroscopy) system with high energy resolution to extract detailed single-particle spectral functions in Bi-2212. Using these spectral functions, we reconstructed both the non-interacting and interacting spin susceptibilities in the normal and superconducting states. The ARPES-derived susceptibilities reveal a broad continuum of spin excitations in the normal state and a sharp spin resonance emerging in the superconducting state due to the collective spin-1 excitation. These results reflect the underlying correlated electron dynamics in Bi-2212 and support the picture of spin fluctuations as a key mediator of high temperature superconductors.

Author dc:creator

• Hao Xu (6530)

• Angle-resolved photoemission spectroscopy

Statement dc:rights

• In Copyright

DOI dc:identifier

https://doi.org/10.25417/uic.31451056.v1

OAI identifier oai:identifier

oai:figshare.com:article/31451056