Enhanced Ferromagnetism of CrI3 Bilayer by Self-Intercalation

TL;DR

This paper introduces a self-intercalation strategy in bilayer CrI3 to significantly enhance its ferromagnetic properties, potentially enabling high-temperature 2D magnetic devices.

Contribution

It proposes a novel self-intercalation method to strengthen ferromagnetism in CrI3 bilayers, demonstrated through first-principles calculations.

Findings

Intercalation induces double exchange effect.

Enhanced interlayer ferromagnetic coupling.

Native atoms act as covalent bridges.

Abstract

Two-dimensional (2D) ferromagnets with high Curie temperature have long been the pursuit for electronic and spintronic applications. CrI3 is a rising star of intrinsic 2D ferromagnets, however, it suffers from weak exchange coupling. Here we propose a general strategy of self-intercalation to achieve enhanced ferromagnetism in bilayer CrI3. We showed that filling either Cr or I atoms into the van der Waals gap of stacked and twisted CrI3 bilayers can induce the double exchange effect and significantly strengthen the interlayer ferromagnetic coupling. According to our first-principles calculations, the intercalated native atoms act as covalent bridge between two CrI3 layers and lead to discrepant oxidation states for the Cr atoms. These theoretical results offer a facile route to achieve high-Curie-temperature 2D magnets for device implementation.