Lifshitz Transition and Nontrivial H-Doping Effect in Cr-based Superconductor KCr${}_3$As${}_3$H${}_x$

Abstract

We report the first-principles study on the H-intercalated Cr-based superconductor KCr${}_3$As${}_3$H${}_x$. Our results show a paramagnetic ground state for KCr${}_3$As${}_3$H. The electronic structure consists of two quasi-one-dimensional (Q1D) Fermi-surfaces and one 3D Fermi-surface which are mainly contributed by Cr-d${}_{z^2}$, d${}_{x^2-y^2}$ and d${}_{xy}$ orbitals. The bare electron susceptibility shows a $\hat{I}“$-centered imaginary peak, indicating possible ferromagnetic spin fluctuations. Upon moderate hole doping, the system undergoes a Lifshitz transition, which may enhance the Q1D feature of the system. The Bader charge analysis and electron localization functions reveal a strong bonding nature of hydrogen in KCr${}_3$As${}_3$H, which results in a nontrivial electron doping in KCr${}_3$As${}_3$H.