Electronic and magnetic properties of monolayer α-RuCl₃: a first-principles and Monte Carlo study

Abstract

Recent experiments revealed that monolayer α-RuCl 3 can be obtain by chemical exfoliation method and exfoliation or restacking of nanosheets can manipulate the magnetic properties of the materials. In this present paper, the electronic and magnetic properties of α-RuCl 3 monolayer are investigated by combining first-principles calculations and Monte Carlo simulations. From first-principles calculations, we found that the spin configuration FM corresponds to the ground state for α-RuCl 3 , however, the other excited zigzag oriented spin configuration has energy of 5 meV/atom higher than the ground state. Energy band gap has been obtained as 3 meV using PBE functionals. When spin-orbit coupling effect is taken into account, corresponding energy gap is determined to be as 57 meV. We also investigate the effect of Hubbard U energy terms on the electronic band structure of α-RuCl 3 monolayer and revealed band gap increases approximately linear with increasing U value. Moreover, spin-spin coupling terms (J 1 , J 2 , J 3 ) have been obtained using first principles calculations. By benefiting from these terms, Monte Carlo simulations with single site update Metropolis algorithm have been implemented to elucidate magnetic properties of the considered system. Thermal variations of magnetization, susceptibility and also specific heat curves indicate that monolayer α-RuCl 3 exhibits a phase transition between ordered and disordered phases at the Curie temperature 14.21 K. We believe that this study can be utilized to improve two-dimensional magnet materials.

Theory and simulations of critical temperatures in CrI3 and other 2D materials: easy-axis magnetic order and easy-plane Kosterlitz-Thouless transitions

“…A somewhat orthogonal approach is to neglect quantum effects completely and perform Monte Carlo (MC) simulations of the classical Heisenberg model. [11][12][13][14] In contrast to renormalized spin-wave theory, the MC approach includes all correlations in the model, but does not take into account the quantum nature of spins. It has recently been shown that the renormalized spin-wave theory yields qualitatively wrong results in systems with large magnetic anisotropy and MC simulations appear to be the most appropriate choice for extracting critical temperatures from Heisenberg models in 2D.…”

Double‐Exchange Magnetic Interactions in High‐Temperature Ferromagnetic Iron Chalcogenide Monolayers

“…where and are the exchange interactions parameter . The exchange parameter J can be obtained by calculating the relative energy differences between ferromagnetic (FM), ferrimagnetic (FiM) and antiferromagnetic states (AFM).…”

“…where J 1 ; J 2 and J 3 are the exchange interactions parameter. [43] The exchange parameter J can be obtained by calculating the relative energy differences between ferromagnetic (FM), ferrimagnetic (FiM) and antiferromagnetic states (AFM). The same Hamiltonian can be used for both molecular approach (MA) as well as for the periodic approach (PA).…”

Exploring the electronic and magnetic properties of new metal halides from bulk to two-dimensional monolayer: RuX3 (X = Br, I)

“…Transition metal trihalides provide a rich family of ma-terials with a wide range of electronic, optical and mechanical properties in which also low dimensional magnetism can be examined, and therefore rapidly increasing theoretical researches exists on this area. [20][21][22][23][24] In our previous study, we systematically investigate the electronic and magnetic properties of an α-RuCl 3 monolayer using DFT and MC simulations, 25 and our cleavage energy calculations give smaller value than that of graphite, which means that the α-RuCl 3 monolayer can be easily obtained from its bulk phase and also we find that it is stable 2D intrinsic ferromagnetic semiconductor. Similarly, a class of 2D ferromagnetic monolayers CrX 3 (X= Cl, Br, I) is studied by Liu et al 26 by using first principle calculations combined with MC simulations based on the Ising Model.…”