Orbital and magnetic ordering in single-layer FePS3: A DFT+U study

Abstract

Among the numerous 2D system that can be prepared via exfoliation, iron phosphorus trisulfide (FePS3) attracts a lot of attention recently due to its broad-range photoresponse, its unusual Ising-type magnetic order and possible applications in spintronic nano-devices. Despite various experimental and theoretical-computational reports, there are still uncertainties in identifying its magnetic ground state. In this paper, we investigate the structural and magnetic properties of single-layer FePS3 by using Density Functional Theory. Our findings show that orbital ordering leads to a variation in distance between pairs of iron atoms by 0.14 Å. These lattice distortions, albeit small, trigger different (ferromagnetic and antiferromagnetic) exchange couplings so that the ground state consists of ferromagnetically aligned zigzag chains along the long Fe -Fe bonds which couple antiferromagnetically along the shorter Fe -Fe bonds. Within the DFT+U framework, we parameterize a spin Hamiltonian including Heisenberg, single-ion anisotropy, Dzyaloshinskii-Moriya and biquadratic interactions. Using U = 2.22 eV gives a consistent description of both the electronic band gap and the Neel temperature in 2D FePS3.

Lattice dynamics, elastic, magnetic, thermodynamic and thermoelectric properties of the two-dimensional semiconductors MPSe3 (M = Cd, Fe and NI): a first-principles study

“…The presence of a soft phonon mode (imaginary frequencies, shown as negative values in the plot) is observed in the trigonal FePSe 3 monolayer around lowest acoustic phonon branches at the Brillouin zone center. This indicates that the FePSe 3 monolayer in this trigonal phase is dynamically unstable, and most likely a distorted ground state with unequal distances between the Fe atoms will result, similar to the one obtained [34,50] for the sulfide FePS 3 . In view of possible applications of the materials in thermoelectric devices, it is worth while to provide a qualitative discussion of their thermal transport properties.…”

“…The layered transition metal trichalcogenides with structural formula ABX 3 where A = Mn and Cr, B = Si and Ge, while X = S, Se and Te have been studied widely as a promising candidates for 2D magnets [20,29,30]. In addition, metal phosphorus trichalcogenides MPX 3 , where M stands for divalent metal ions such as Mn, Cd, Fe, Ni, Cu, Zn etc while X = S, Se and Te [17,18,[31][32][33][34] have been predicted to be intriguing materials which can notably enhance the applications of 2D materials in a broad wavelength spectrum. Their exceptional and distinct structural, magnetic and physio-chemical properties have motivated this present study.…”