Stacking-controlled magnetic exchange and magnetoelectric coupling in bilayer CrI₂

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Chemistry

Background:

• Chromium diiodide (CrI₂) is a material with potential for spintronic applications.
• Understanding the interplay between electronic, magnetic, and structural properties is crucial for material design.

Purpose of the Study:

• To investigate the electronic and magnetic properties of chromium diiodide (CrI₂) bilayers using first-principles calculations.
• To establish the hierarchy of magnetic interactions across different stable stacking registries.
• To explore the potential for magnetoelectric coupling and tunability in CrI₂ bilayers.

Main Methods:

• First-principles calculations were employed to simulate CrI₂ bilayers.
• Analysis of electronic band structure and magnetic exchange interactions.
• Investigation of symmetry properties and the emergence of Dzyaloshinskii-Moriya terms.

Main Results:

• The monolayer CrI₂ exhibits an x-stripe antiferromagnetic ground state.
• The BA' stacking configuration is the most stable for bilayers, featuring antiparallel interlayer magnetic alignment.
• Bilayer stacking significantly influences in-plane magnetic exchange (6-10% increase) and introduces registry-dependent interlayer exchange.
• Non-centrosymmetric stacking generates Dzyaloshinskii-Moriya terms, leading to in-plane polarizations up to ~10 μC cm^-2 and direct magnetoelectric coupling.
• Stacking configurations act as selectors for magnetic anisotropy and drivers for magnetoelectricity.

Conclusions:

• Bilayer CrI₂ exhibits tunable magnetism and register-dependent polarization, driven by stacking configuration.
• Mechanical reconfiguration via interlayer sliding is feasible, with energy differences compatible with experimental actuation.
• These findings present promising opportunities for novel spintronic devices leveraging tunable magnetic states and electric dipoles.