Monolayer CrSBr is a recently discovered semiconducting spin-3/2 ferromagnet with a Curie temperature of around 146 K. In contrast to many other known 2D magnets, the orthorhombic lattice of CrSBr gives rise to spatial anisotropy of magnetic excitations within the 2D plane. Triaxial magnetic anisotropy and considerable magnetic dipolar interactions in CrSBr challenge its theoretical description in terms of spin Hamiltonians. Here, we employ a Green’s function formalism combined with first-principles calculations to study the magnetic properties of monolayer CrSBr in different regimes of surrounding dielectric screening. In the free-standing limit, the system is close to an easy-plane magnet, whose long-range ordering is partially suppressed. On the contrary, in the regime of large external screening, monolayer CrSBr behaves like an easy-axis ferromagnet with more stable magnetic ordering. Our findings suggest that anisotropic layered magnets form a potentially promising platform for studying the effects of substrate screening on magnetic ordering in 2D.

单层 CrSBr 是最近发现的半导体自旋 3/2 铁磁体，其居里温度约为 146 K。与许多其他已知的二维磁体相比，CrSBr 的正交晶格在二维平面内产生磁激发的空间各向异性。CrSBr 中的三轴磁各向异性和相当大的磁偶极相互作用挑战了其在自旋哈密顿量方面的理论描述。在这里，我们采用格林函数形式主义结合第一性原理计算来研究单层 CrSBr 在不同的周围电介质屏蔽方案中的磁性。在独立极限下，系统接近易平面磁体，其长程有序被部分抑制。相反，在大型外部筛选制度中，单层 CrSBr 表现得像易轴铁磁体，具有更稳定的磁序。我们的研究结果表明，各向异性层状磁体形成了一个潜在的有前途的平台，用于研究基板筛选对 2D 磁排序的影响。