High-Curie-temperature ferromagnetism in bilayer CrI3 on bulk semiconducting substrates

TL;DR

This paper demonstrates a strategy to induce and enhance ferromagnetism in bilayer CrI3 on semiconducting substrates, significantly increasing its Curie temperature for potential electronic and spintronic applications.

Contribution

It introduces a substrate-induced doping method to switch bilayer CrI3 from antiferromagnetic to ferromagnetic state, boosting its Curie temperature.

Findings

Substrate proximity effect induces ferromagnetism in bilayer CrI3.

Electronic doping from substrates enhances exchange interactions.

Theoretical predictions show potential for high-temperature 2D ferromagnets.

Abstract

Two-dimensional (2D) ferromagnetic (FM) semiconductors with high Curie temperature have long been pursued for electronic and spintronic applications. Here we provide a general strategy to achieve robust FM state in bilayer CrI3 of the monoclinic stacking, which intrinsically has interlayer antiferromagnetic (AFM) order and weak in-plane FM coupling. We showed that the proximity effect from bulk semiconducting substrates induces electronic doping and significantly increases the FM nearest-neighbor exchange for bilayer CrI3, leading to the AFM-to-FM transition for the interlayer spin configuration as well as enhanced intralayer FM coupling. By first-principles calculations and Monte Carlo simulations, bulk and 2D semiconductors providing different interaction strengths from strong covalent bonding to weak van der Waals (vdW) interaction with CrI3 are compared to thoroughly address the substrate effect on magnetic behavior and Curie temperature of bilayer CrI3. These theoretical results offer a facile route for direct synthesis of 2D ferromagnets on proper semiconducting substrates to achieve high Curie temperature for device implementation.