  Monolayer CrSBr is a recently discovered semiconducting spin-3/2 ferromagnet
with a Curie temperature around 146 K. Unlike many other known two-dimensional
(2D) magnets, CrSBr has an orthorhombic lattice, giving rise, for instance, to
spatial anisotropy of the magnetic excitations within the 2D plane. Theoretical
description of CrSBr within a spin Hamiltonian approach turns out to be
nontrivial due to the triaxial magnetic anisotropy as well as due to magnetic
dipolar interactions, comparable to spin-orbit effects in CrSBr. Here, we
employ a Green's function formalism combined with first-principles calculations
to systematically study the magnetic properties of monolayer CrSBr in different
regimes of surrounding dielectric screening. We find that the magnetic
anisotropy and thermodynamical properties of CrSBr depend significantly on the
Coulomb interaction and its external screening. In the free-standing limit, the
system turns out to be 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. Despite being relatively large, the magnetic dipolar
interactions have only little effect on the magnetic properties. Our findings
suggests that 2D CrSBr is suitable platform for studying the effects of
substrate screening on magnetic ordering in low dimensions.

Materials Science;Strongly Correlated Electrons