High-temperature quantum anomalous Hall insulator in two-dimensional Bi2ON

Abstract

Chiral edge states in quantum anomalous Hall (QAH) insulators can conduct dissipationless charge current, which has attracted extensive attention recently. One major obstacle for realistic applications is the lack of suitable room-temperature QAH systems, especially with both robust ferromagnetic (FM) order and large gaps. Here, based on first-principles, we report a long-sought high temperature QAH system in the Bi (111) film asymmetrically functionalized with nitrogen and oxygen. The FM Curie temperature is as high as 420 K, while the nontrivial bulk gap reaches up to 454 meV, rendering that the QAH effect can readily be observed at room temperature or even high temperature. Further analysis of the gapless chiral edge states, Chern number (C = 1), and quantized QAH conductivity offers solid evidence of its nontrivial feature. Our work provides an opportunity for realizing the high-temperature QAH effect and fabricating energy-efficient spintronics operating at room temperature.