Tuning magnetic properties of Cr2M2C3T2 (M = Ti and V) using extensile strain

The influence of extensile strain on the magnetic properties of Cr2M2C3T2 (M = Ti, V, Nb, and Ta; T = OH, O, and F) are investigated using density functional theory. Calculation results show that the ferromagnetic arrangement is energetically favorable for Cr2Ti2C3O2 and Cr2V2C3O2 in the strain-free state. The Curie temperatures are 720.6 K and 246.8 K, respectively, calculated using the Heisenberg model with mean-field approximation. Other systems are anti-ferromagnetic with magnetic moment of Cr atoms (MCr) larger than 1.9 μB. For extensile strains that vary from −5% to 5%, the anti-ferromagnetic arrangement is always energetically favorable for Cr2Nb2C3T2 and Cr2Nb2C3T2 systems. However, ferromagnetic to anti-ferromagnetic (or anti-ferromagnetic to ferromagnetic) phase transitions occurred for Cr2Ti2C3T2 and Cr2V2C3T2, but not Cr2Ti2C3O2. The magnetic moment of Cr atoms increases monotonically as extensile strain increases from −5% to 5% for all Cr2M2C3T2 systems. The projected density of states shows that Cr-3d orbitals become more localized as the strain increases, and that the density of states near the fermi level decreases, which may reduce the conductivity. This study indicates that the magnetic and electronic properties of Cr2M2C3T2 (where M = Ti, or V; T = O, OH, or F) can be effectively tuned using extensile strain. This promotes the application of these two-dimensional materials in spin electronics and data storage.