Doping evolution of the normal state magnetic excitations in pressurized La₃Ni₂O₇

Abstract

The doping evolution behaviors of the normal state magnetic excitations
(MEs) of the pressurized nickelate La3Ni2O7 are theoretically studied in this paper. It
was found that the MEs of the parental compound have very strong dependence on the
vertical momentum qz. For small qz, the low energy MEs exhibit a square-like pattern
centered at (0, 0) which originates from the intrapocket particle-hole scatterings. With
the increasing of qz, this square pattern diminishes gradually, and the MEs turn to be
ruled by two new interpocket scattering modes with significantly larger intensity for
qz around π. Hence, we have established the exotic qz evolution of the normal state
MEs of the bilayer nickelates in the present study. Furthermore, we find that the main
features of the MEs are very robust against doping. They persist in the wide hole- or
electron-doping regime around the filling of n = 3.0. However, in the heavily electrondoped
regime, the behaviors of the MEs change qualitatively due to the occurrence of
a Lifshitz transition. With the absence of the hole γ pocket, for n = 4.0, there will
exist nearly perfect nesting between the electron α and the hole β pockets guaranteed
by the Luttinger theorem and the Fermi surface topology. As a result, a spin-densitywave
(SDW) phase was theoretically predicted to order around (π, π, π) near n = 4.0,
in contrast with the parental compound which orders at (π/2, π/2, π) under ambient
pressure. We expect that the doping-temperature phase diagram of the pressurized
La3Ni2O7 will be explored in the near future which is helpful to unravel the intricate
relation between the magnetic order and superconductivity.