Room-temperature antiferromagnetic order in monolayer Fe2C

We have studied the room-temperature long-range antiferromagnetic order in the Fe2C monolayer using the combination of first-principles calculations and the Green's function analysis within the anisotropic Heisenberg model. The Fe2C monolayer is a semimetal with the out-of-plane antiferromagnetic order between two Fe planes. The Green's function approach within the random phase approximation is formulated to calculate the temperature-dependent antiferromagnetic magnon energy and the spin correlation function in a two-dimensional antiferromagnetic monolayer. The correlation function is used to evaluate the sublattice magnetization and study the magnetic phase transition in monolayer Fe2C. Moreover, the spin Hamiltonian and the Green's function formalism are developed to investigate the antiferromagnetic Fe2C monolayer in the presence of an external magnetic field applied along the easy axis. The H-T phase diagram shows that the antiferromagnetic to spin-flop and the spin-flop to paramagnetic phase transitions occur in low temperatures. Finally, we estimate the Neel temperature and the critical values of the magnetic field strength for these two phase transitions.

Automated summary

In this study, the room-temperature long-range antiferromagnetic order in the Fe2C monolayer was investigated using first-principles calculations and Green's function analysis. The Fe2C monolayer was found to be a semimetal with out-of-plane antiferromagnetic order between two Fe planes. By calculating the temperature-dependent antiferromagnetic magnon energy and spin correlation function, the sublattice magnetization and magnetic phase transition in monolayer Fe2C were evaluated. Furthermore, the effects of an external magnetic field on the antiferromagnetic Fe2C monolayer along the easy axis were investigated, revealing phase transitions from antiferromagnetic to spin-flop and spin-flop to paramagnetic at low temperatures. The Neel temperature and critical values of the magnetic field strength for these transitions were also estimated.