Interlayer Exchange Interaction Driven Topological Phase Transition in Antiferromagnetic Electride Gd$_2$O
Abstract
Based on first-principles calculations, we discover a two-dimensional layered antiferromagnetic (AFM) electride GdO, where anionic excess electrons exist in the interstitial spaces between positively charged cationic layers. It is revealed that each cationic layer composed of three-atom-thick GdOGd stacks has in-plane ferromagnetic and out-of-plane AFM superexchange interactions between the localized Gd 4 spins through O 2 orbitals. Furthermore, the interlayer superexchange mediated by the hybridized Gd-5 and interstitial--like states involves intimate couplings between the spin, lattice, and charge degrees of freedom, thereby inducing simultaneous magnetic, structural, and electronic phase transitions. The resulting ground state with the simple hexagonal lattice hosts massless Dirac fermions protected by nonsymmorphic magnetic symmetry, as well as massive Dirac fermions. We thus demonstrate that the anionic excess electrons in GdO play a crucial role in the emergence of magnetic Dirac semimetal states, therefore offering an intriguing interplay between 2D magnetic electrides and topological physics.
Cite
@article{arxiv.2109.09325,
title = {Interlayer Exchange Interaction Driven Topological Phase Transition in Antiferromagnetic Electride Gd$_2$O},
author = {Shuyuan Liu and Chongze Wang and Hyunsoo Jeon and Jeehoon Kim and Jun-Hyung Cho},
journal= {arXiv preprint arXiv:2109.09325},
year = {2022}
}