Spin-canting-driven triple coupling of spin, electric, and valley polarization in two-dimensional antiferromagnetic semiconductors

Antiferromagnets have aroused widespread interest in spintronics due to negligible stray field and ultrafast spin dynamics. However, antiferromagnets are usually difficult to exhibit the versatile functional properties featured by ferromagnetic materials, particularly the multiple coupling effect among spin, charge, and orbital. Here, based on first-principles calculations, we propose that by exploiting magnetic-field-induced spin canting, the triple coupling of spin, electric, and valley polarization in antiferromagnetic semiconductors can be easily achieved. Taking the two-dimensional (2D) antiferromagnetic semiconductors ${\mathrm{MnPS}}_{3}$ and ${\mathrm{MnPSe}}_{3}$ as examples, we demonstrate the occurrence of ferroelectricity and magnetization driven by different canted-antiferromagnetic orders, and their controllability by both electric and magnetic fields. Remarkably, spin canting further results in bipolar magnetic semiconductor properties with reversible spin polarization and valley polarization in valence and conduction bands. Moreover, we illustrate that such spin-driven multiferroics is derived from the subtle interaction of lattice and spin order. This work paves the way to explore magnetoelectric coupling and valley polarization in 2D antiferromagnetic semiconductors.