Fermi Surface Nesting with Heavy Quasiparticles in the Locally Noncentrosymmetric Superconductor CeRh_2As_2
arXiv (Cornell University)(2023)
Abstract
The locally noncentrosymmetric heavy fermion superconductor CeRh_2As_2
has attracted considerable interests due to its rich superconducting phases,
accompanied by a quadrupole density wave and pronounced antiferromagnetic
excitations. To understand the underlying physics, we here report measurements
from high-resolution angle-resolved photoemission. Our results reveal fine
splittings of the conduction bands related to the locally noncentrosymmetric
structure, as well as a quasi-two-dimensional Fermi surface (FS) with strong
4f contributions. The FS exhibits nesting with an in-plane vector (π/a,
π/a), which is facilitated by the van Hove singularity near X̅ that
arises from the characteristic conduction-f hybridization. The FS nesting
provides a natural explanation for the observed antiferromagnetic excitations
at (π/a, π/a), which could be intimately connected to its
unconventional superconductivity. Our experimental results are well supported
by density functional theory plus dynamical mean field theory calculations,
which can capture the strong correlation effects. Our study not only provides
spectroscopic proof of the key factors underlying the field-induced
superconducting transition, but also uncovers the critical role of FS nesting
and lattice Kondo effect in the intertwined spin and charge fluctuations.
MoreTranslated text
Key words
heavy quasiparticles,quasi-two-dimensional
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