Raising the Curie Temperature of Two-Dimensional Semiconducting CrSbr by van der Waals Coupling with In-Plane Ferroelectric GeS

For most multiferroics, the combination of ferromagnetism and ferroelectricity holds unprecedented promise for high-density and low-power polymorphic storage. In contrast to single-phase multiferroics, which cannot achieve strong magnetoelectric coupling at room-temperature, heterostructure coupling is an effective strategy. In this work, based on first-principles calculations, the magnetoelectric coupling in the CrSBr/GeS heterostructure is investigated. As a representative of 2D ferromagnetic materials, CrSBr can be exfoliated from a layered bulk crystal, but its Curie temperature (TC) remains well below room temperature. GeS is an experimentally preparable ferroelectric semiconductor with in-plane polarization. The interfacial coupling in the heterostructure not only facilitates charge transfer but also provides a new exchange coupling path for Cr in the ferromagnetic CrSBr, further increasing the TC of the magnetic system. In addition, both in-plane strain and back-gate electric field can regulate the electric polarization intensity of FE GeS, which further affects the charge distribution and coupling of the interface and changes the TC of the magnetic layer. With a 5% tensile strain along the a-axis direction, the TC of CrSBr increases to 246 K, while the in-plane polarization of GeS decreases to 3.71 × 10–10 C/m. These results show that CrSBr/GeS multiferroic heterostructures provide a multiknob research platform for magnetoelectric coupling and high-density memory devices.