Magnetism in single-layer of Zrse[formula omitted] by substituting 3[formula omitted] transition metals for Zr: Structural symmetry versus exchange splitting

Abstract

To understand the magnetic properties of the novel two-dimensional materials and other phenomena which depend on electron correlation, finding the states located around Fermi energy (EF) and contributing to the correlated states of the system is basically important. In this paper, using the density functional theory, we investigate the electronic properties of substitution of 3d transition metal (TM) atoms for Zr in trigonal prismatic 2H and octahedral 1T structure of monolayer TM-doped ZrSe2 materials. The band structure, orbital projected density of states (DOS), and the number of electrons in the d-shell show that the correlated subspace depends strongly on the structural phase of the systems. The case of Mn substitution has the highest magnetic moment, 2.91 μB and 3.30 μB in 2H and 1T phases, respectively. In the 1T structure of Mn-doped ZrSe2, almost partially filled t2g impurity bands is well separated from eg states in the non-magnetic calculation, having a small bandwidth of about Wb= 0.4 eV. As a consequence, the strength of electron correlation U/Wb increases (U is effective on-site Coulomb interaction) and puts this compound in the moderately or strongly correlated regime, and causes a stronger electron spin separation than the 2H phase. In the 2H phase, the correlated states include two impurity bands with dominantly dxy and dx2−y2 characters and induce a smaller magnetic moment. Due to the large DOS of Mn and Cr atoms at the EF in both 1T and 2H structures, the Stoner criterion I.D(EF)>1 is satisfied, which is reasonably consistent with our results of ferromagnetic total energy calculations and the sizable magnetic moments.