Preparation and multiferroicity of a novel two-dimensional material NiH2SeO4

Abstract

Two-dimensional materials have rich physical and chemical properties due to their unique nanostructures and electronic states. Although many two-dimensional materials have been reported in the past decade, they rarely exhibit multiferroic behavior. Herein, we synthesized layered structure NiH₂SeO₄ single crystals using the hydrothermal method, which can be further exfoliated into nanosheets using the transparent glue method. In addition, we demonstrated using first-principles calculations that the dissociation energy and dissociation strength of NiH₂SeO₄ crystals are much lower than those of graphite, and the single layer is multiferroic. The monolayer NiH₂SeO₄ is mainly polarized along the in-plane axis, and the polarization is comparable to the bulk material of BaTiO₃. Furthermore, NiH₂SeO₄ exhibits antiferromagnetic transition at 24 K, and the effective moment of Ni²⁺ is 3.32 μ_B. The monolayer NiH₂SeO₄ is antiferromagnetic and the easy axis is along the in-plane (100) direction. NiH₂SeO₄ represents one of a few two dimensional multiferroic materials, and this study provides an approach for obtaining two dimensional multiferroic materials by incorporating magnetic ions with ions with lone pairs.