Magnetic properties of monolayer, multilayer, and bulk CrTe$_2$

TL;DR

This study explores the magnetic properties of CrTe$_2$ across monolayer, multilayer, and bulk forms using DFT and DFT+DMFT, revealing layer-dependent magnetic interactions and phase tendencies.

Contribution

It provides a comprehensive analysis of CrTe$_2$'s magnetic phases and interactions, highlighting the impact of layer number and substrate effects on magnetic order.

Findings

Monolayer CrTe$_2$ favors a 120° antiferromagnetic structure.

Bilayer and trilayer CrTe$_2$ exhibit ferromagnetic intra-layer and antiferromagnetic inter-layer interactions.

Bulk CrTe$_2$ shows a temperature-dependent transition from ferromagnetic to antiferromagnetic correlations.

Abstract

We investigate magnetic properties of CrTe$_2$ within the density functional theory (DFT) approach in ferromagnetic phase and combination of DFT and dynamical mean field theory (DFT+DMFT) approach in paramagnetic phase. We show that few layer CrTe$_2$ possesses well formed local magnetic moments. In the single layer CrTe$_2$ we find antiferromagnetic exchange with 120\degree antiferromagnetic structure most preferable. In the bilayer and trilayer systems electronic correlations in DFT+DMFT approach yield ferromagnetic exchange interaction within each layer, but the interaction between the layers is antiferromagnetic, such that alternation of the direction of magnetization of the layers is expected. In bulk CrTe$_2$ we find the tendency to ferromagnetic order at low temperature, but with increase of temperature antiferromagnetic correlations between the layers dominate. Determination of the critical number of layers at which the interlayer antiferromagnetic order changes to the ferromagnetic one, likely requires consideration of the non-local Coulomb interactions. Erratum: In our study [A. A. Katanin, E. M. Agapov, Phys. Rev. B 111, 035118 (2025)] we found for the monolayer CrTe$_2$ the most preferable 120\degree spin spiral structure. While this order is expected for freely suspended CrTe$_2$, for experimentally realized single layer CrTe$_2$ on a substrate, which is characterized by larger lattice constant, the momentum dependence of the susceptibilities drastically changes. In particular, the ferromagnetic ground state is expected for this compound, in agreement with the experimental data.