Ferroelectric control of bipolar magnetic semiconductor with room Curie temperature

TL;DR

This paper proposes a new two-dimensional ferroelectric-controlled bipolar magnetic semiconductor with a Curie temperature above room temperature, enabling nonvolatile electrical control for spintronic applications.

Contribution

It introduces a novel 2D ferroelectric-controlled bipolar magnetic semiconductor with room-temperature ferromagnetism and demonstrates a feasible nonvolatile memory device design.

Findings

Cr2NiSe4 exhibits a 0.40 eV band gap and 352 K Curie temperature.

Switching ferroelectric polarization induces BMS-to-half-metal transition.

The proposed memory device uses ferroelectric polarization for writing and spin polarization for reading.

Abstract

The development of room-temperature tunable magnetic semiconductors is crucial for the advancement of low-power, high-performance information technologies. Using density functional theory calculations, we propose a series of two-dimensional magnetic semiconductors with critical temperature above room temperature, including three ferromagnetic and two antiferromagnetic semiconductors.Their stability is confirmed through phonon spectra, molecular dynamics simulations, and formation energy calculations. In particular, we demonstrate a ferromagnetic bipolar magnetic semiconductor (BMS), Cr2NiSe4, formed via Ni intercalation into bilayer CrSe2, which exhibits a 0.40 eV band gap and a Curie temperature of 352 K. Nonvolatile carrier spin polarization control in Cr2NiSe4 is achieved by switching the ferroelectric polarization of an Al2Se3 substrate. Switching the ferroelectric state of monolayer Al2Se3 induces a BMS-to-half-metal transition. Reversing the polarization of bilayer Al2Se3 yields a half-metallic Cr2NiSe4 with fully opposite carrier spin polarization. Furthermore, we propose a multiferroic nonvolatile memory design: write operations are controlled by the ferroelectric polarization state of bilayer Al2Se3, while read operations rely on detecting the distinct carrier spin polarizations of Cr2NiSe4. Our work reports a two dimensional BMS with Curie temperature above room temperature and presents a feasible strategy for its nonvolatile electrical control.