Effects of the vacancy and doping on the electronic and magnetic characteristics of ZrSe2 monolayer: A first-principles investigation

Based on the first-principles under the framework of density functional theory, we report the studies of vacancy defects and substitution doping on the electronic and magnetic characteristics of ZrSe2 monolayer (ZrSe2-ML). The results reveal that the non-magnetic semiconductor (SC) material ZrSe2 has magnetic metal behavior by producing one Zr vacancy (V1Zr) as well as one Zr and one Se di-vacancy (V1Zr+1Se), the net moments are 1.756 and 1.295 mu B, and both originate from the Se atoms around the vacancies. The one Se vacancy (V1Se) system exhibits the metal behavior, while the one Zr and two Se tri-vacancy (V1Zr+2Se) system still maintains the characteristics of a non-magnetic SC. In addition, a transition metal (TM) atom X is used to replace one Zr atom in the non-magnetic SC material ZrSe2, which can also induce magnetism or has metallic behavior. The Cr-, Mn-, Mo-, Tc-, W- and Re-doped systems exhibit the magnetic behavior with moments are 2.482, 3.000, 2.130, 2.999, 2.000, 2.999 mu B, respectively. The moments are proportional to the number of unpaired electrons remaining on the d orbitals of TM atoms. These systems have metallic characteristic of Cr- and Mo-doped. The Mn-, Tc- and Redoped systems still maintain SC characteristic. In particular, the W-doped ZrSe2-ML is half-metal. The calculated values show that under the condition of Se-rich, it is energetically favorable and relatively easy to dope TM atom into ZrSe2-ML.