Intrinsic Quantum Anomalous Hall Effect with In-Plane Magnetization: Searching Rule and Material Prediction

Abstract

So far, most theoretically predicted and experimentally confirmed quantum anomalous Hall effect (QAHE) are limited in two-dimensional (2D) materials with out-of-plane magnetization. In this Letter, starting from 2D nodal-line semimetal, a general rule for searching QAHE with in-plane magnetization is mapped out. Due to the spin-orbital-coupling, we found that the magnetization will prefer an in-plane orientation if the orbital of degenerate nodal-line states at Fermi-level have the same absolute value of magnetic quantum number. Moreover, depending on the broken or conserved mirror symmetry, either QAHE or 2D semimetal can be realized. Based on first principles calculations, we further predict a real material of monolayer LaCl to be an intrinsic QAHE with in-plane magnetization. By tuning the directions of in-plane magnetization, the QAHE in LaCl demonstrates a threefold rotational symmetry with Chern number of either +1 or −1, and the transition point is characterized by a 2D semimetal phase. All these features are quantitatively reproduced by tight-binding model calculations, revealing the underlying physics clearly. Our results greatly extend the scope for material classes of QAHE, and hence stimulate immediate experimental interests.

Controlling bimerons as skyrmion analogues by ferroelectric polarization in 2D van der Waals multiferroic heterostructures

“…In this work, we propose a LaCl/In 2 Se 3 multiferroic HS, where In 2 Se 3 is an ideal 2D FE material with controllable out-of-plane spontaneous polarization 24,[39][40][41] , while LaCl was synthesized decades ago and proved to be a vdW layer compound [42][43][44][45] . Furthermore, LaCl monolayer as an easy-plane FM metal has been confirmed in many works [46][47][48][49] . In addition, La-5d orbital has a strong spin-orbit coupling, which satisfies the requirement of producing strong Dzyaloshinskii-Moriya interaction, i.e., a necessary condition for the generation of magnetic chiral skyrmions.…”

Electrides: a review

“…[142][143][144] Incidentally, several predicted topological materials were later shown to also be electrides. For example, a quantum anomalous Hall insulator LaBr, [145][146][147] quantum spin Hall system HfBr, and a nodal-line semimetal Sr 2 Bi. 136 Thus, the nature of topological states and electride electronic configuration are closely related.…”

High-throughput design of magnetic materials

“…Nevertheless, the characterization of the other properties for 2D materials in the HTP manner is still limited. One exception is the HTP screening for QAHC with in-plane magnetization [581], where the prototype LaCl might not be a stable 2D compound. It is noted that there have been a big number of predictions on 2D magnetic and nonmagnetic materials hosting exotic properties but the feasibility to obtain such compounds has not been systematically addressed.…”