Electric field induced antiferromagnetic to ferromagnetic transition and thermal conductivity reduction in MnSe monolayers

Active regulation of the magnetic state in two-dimensional (2D) antiferromagnetic (AFM) materials through electric fields is a highly promising technology owing to extensive applications of nanospintronic devices. In this paper, we find that an electric field can induce AFM to ferromagnetic (FM) states in MnSe monolayer around room temperature, along with an electric field strength of $1.9\phantom{\rule{0.16em}{0ex}}\mathrm{V}/\AA{}$. Fortunately, applying a biaxial tensile strain of 1.8% can reduce the AFM-FM threshold voltage by a factor of 10 owing to the magnetoelastic coupling effect induced by strain. A theoretical model based on Kugel-Khomskii theory is developed to explain the impact of strain and electric field on magnetic state, which is applicable to other 2D antiferromagnets. Moreover, this AFM-FM phase transition increases spin-phonon coupling strength and decreases the frequency of vibration modes. These effects enhance the phonon anharmonicity and reduce room-temperature thermal conductivity, demonstrating active regulation of the thermal conductivity of MnSe monolayers. This study not only provides a unique approach to regulated 2D magnetic materials but also designs high-performance 2D room-temperature thermal switching.