Two-dimensional multiferroic metal with voltage-tunable magnetization and metallicity

TL;DR

This paper proposes a novel 2D multiferroic metal that exhibits voltage-tunable magnetization and metallicity, achieved through hole doping and defect engineering, expanding the possibilities for 2D multiferroic materials.

Contribution

It introduces a new design principle for 2D multiferroic metals that do not rely on transition metals, enabling electrical control of magnetization and metallicity.

Findings

Magnetoelectric effect demonstrated in doped monolayer { extalpha}-In2Se3

Electrical switching of magnetization and metallicity via surface charge manipulation

Charge disproportionation controlled by strain and defect-polarization coupling

Abstract

We design a multiferroic metal that combines seemingly incompatible ferromagnetism, ferroelectricity, and metallicity by hole doping a two-dimensional (2D) ferroelectric with high density of states near the Fermi level. The strong magnetoelectric effect is demonstrated in hole-doped and arsenic-doped monolayer {\alpha}-In2Se3 using first-principles calculations. Taking advantage of the oppositely charged surfaces created by an out-of-plane polarization, the 2D magnetization and metallicity can be electrically switched on and off in an asymmetrically doped monolayer. The substitutional arsenic defect pair exhibits an intriguing electric field-tunable charge disproportionation process accompanied with an on-off switch of local magnetic moments. The charge ordering process can be controlled by tuning the relative strength of on-site Coulomb repulsion and defect dipole-polarization coupling via strain engineering. Our design principle relying on no transition metal broadens the materials design space for 2D multiferroic metals.