Intercalated transition metal dichalcogenides as platform for altermagnetism: a first principles study

Altermagnetism is a novel type of magnetic order that allows systems with no net magnetic moment to display properties traditionally associated with ferromagnets, such as spin splitting and anomalous Hall effect, due to preserving certain combinations of real-space and time-reversal symmetries. Recently, altermagnetism has been identified in intercalated transition metal dichalcogenides (TMDs) VNb₃S₆ and CoNb₄Se₈. These intercalated TMDs form a more general family M_x(TM)(S/Se)₂ (M = metal, TM = transition metal) which is known to order in a superlattice for simple fractional fillings (x=1/4, x=1/3). These superlattices have two intercalant sites per unit cell related by a non-symmorphic symmetry, making them a potential general platform for realizing altermagnetism. In this work, we characterize the magnetic properties and preferred magnetic states for this family of materials using density functional theory (DFT) and quantitatively determine their spin splittings to pinpoint the most promising candidates to pursue.