Competing multiferroic phases in monolayer and few-layer NiI2

2024/05/13 by Nanshu Liu, Cong Wang, Changlin Yan +4 · 1 voice
Materials Science · #2D Materials and Applications #MXene and MAX Phase Materials #Multiferroics and related materials

paper · doi:10.1103/physrevb.109.195422

openalex publication_date 2024/05/13 · openalex created_date 2024/05/14 · openalex updated_date 2026/07/30

Abstract

A recent experiment reported type-II multiferroicity in monolayer (ML) NiI₂ based on a presumed spiral magnetic configuration (spiral-B), which is, as we found here, under debate in the ML limit. Freestanding ML NiI₂ breaks its C₃ symmetry, as it prefers a striped antiferromagnetic order (AABB-AFM) along with an intralayer antiferroelectric (AFE) order. However, substrate confinement may preserve the C₃ symmetry and/or apply tensile strain to the ML. This leads to another spiral magnetic order (spiral\ensuremath-IV^X), while bilayer shows a different order (spiral\ensuremath-V^X) and spiral-B dominates in thicker layers. Thus, three multiferroic phases, namely, spiral-B+FE, spiral\ensuremath-IV^X+FE, spiral\ensuremath-V^X+FE, and an antimultiferroic AABB-AFM+AFE one, show layer thickness dependence and geometry-dependent dominance, ascribed to competition among thickness-dependent Kitaev, biquadratic, and Heisenberg spin-exchange interactions and single-ion magnetic anisotropy. Our theoretical results clarify the debate on the multiferroicity of ML NiI₂ and shed light on the role of layer stacking induced changes in noncollinear spin-exchange interactions and magnetic anisotropy in thickness-dependent magnetism.

Citations

• Projector augmented-wave method
• Semiempirical GGA‐type density functional constructed with a long‐range dispersion correction
• Efficient iterative schemes forab initiototal-energy calculations using a plane-wave basis set
• Multiferroic materials and magnetoelectric physics: symmetry, entanglement, excitation, and topology
• From ultrasoft pseudopotentials to the projector augmented-wave method

Discussions

• I am currently trying to understand how to model the intralayer magnetic exchange tensor in NiI $_2$ . The relevant terms for this purpose have a contribution to the configurational energy as follows [stackexchange, 1 points]

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