Stacking tunable interlayer magnetism in bilayer <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>CrI</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math>

Abstract

Interlayer magnetic interactions between two-dimension van der Waals layers are often thought to be weak or even negligible and their mechanism is largely unexplored. Here, the authors propose a mechanism for these interactions in a CrI${}_{3}$ bilayer, based on the concept of covalent-like quasibonding, which offers significant alteration of interlayer wave-function hybridization but small energetic difference between different stacking configurations. While a near-collinear coupling between two parallel spin-polarized I 5$p$ orbitals prefers interlayer ferromagnetism, a noncollinear one favors antiferromagnetism, which is tunable by surmounting a tiny energy barrier between two stacking orders. This explains experimental observations and suggests a strategy for designing interlayer magnetism.