Competing phases in transition metal dichalcogenides: charge density waves and magnetism

The appearance of a ferromagnetic long-range order phase in two-dimensional materials is hampered by the Mermin-Wagner theorem that requires the breakup of spin-rotational invariance via, e.g. a perpendicular magnetic anisotropy in the monolayer limit. Transition metal dichalcogenides are promising candidates to show long-range ferromagnetic order in the ultra-thin limit by overcoming the restrictions of the Mermin-Wagner theorem. However, the characterization of these materials is complex because of the vast amount of electronic and structural phases that compete as the materials are grown thinner and thinner. In this talk, we will summarize our findings in the family of V- and Cr-based transition metal dichalcogenides. We have carried out ab initio calculations in various of these systems analyzing how the different charge-density waves that can be stabilized compete with magnetism, and also how these can be tuned via different mechanisms, such as: strain, stoichiometry, heterostructuring, etc. Our ab initio calculations suggest routes to enhance the ferromagnetic long-range order by understanding how to control the stability of the charge-density waves in these systems.