Magnetic Properties of Single Layer Fes2, Fese2 And Fete2

Over the past few years, there has been a growing fascination with the distinctive features of magnetic two-dimensional materials. Single layer structures with magnetic properties hold significant potential for diverse applications. This study employs first principles calculations to examine the electronic, structural, and magnetic properties of the FeX2 monolayers. It is observed that all FeX2 monolayers exhibit ferromagnetic behavior. Additionally, the research includes electronic, vibrational properties and Curie temperatures of the FeX2 monolayers for the two phases, namely hexagonal and trigonal. Calculated temperatures using Monte Carlo are found to be 1330, 1032, and 1013 K in the H phase and 534, 453, and 149 K in the T phase of the FeS2, FeSe2, and FeTe2, respectively. The Curie temperatures are also estimated using mean field approximation based on energy difference of the two magnetic configuration. The results are calculated as 925, 1488, 1487 K in the H phase, and 661, 459, and 134 K in the T phase for FeS2, FeSe2, and FeTe2, respectively. Regarding the electronic ground state, all configurations exhibit metallic behavior. However only two FeX2 configurations show dynamic stability. Specific heat and magnetic susceptibility exhibit significant fluctuations around the predicted critical temperature during thermalization.