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 La _3 Ni _2 O _7 are theoretically studied in this paper. It was found that the MEs of the parental compound have very strong dependence on the vertical momentum q _z . For small q _z , 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 q _z , this square pattern diminishes gradually, and the MEs turn to be ruled by two new interpocket scattering modes with significantly larger intensity for q _z around π . Hence, we have established the exotic q _z 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 electron-doped 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-density-wave phase was theoretically predicted to order around $(\pi,\pi,\pi)$ near n = 4.0, in contrast with the parental compound which orders at $(\pi/2,\pi/2,\pi)$ under ambient pressure. We expect that the doping-temperature phase diagram of the pressurized La _3 Ni _2 O _7 will be explored in the near future which is helpful to unravel the intricate relation between the magnetic order and superconductivity.

Keywords

• high temperature superconductors
• magnetic excitations
• unconventional superconductivity
• spin-density-wave order