Electronic structure and magnetic properties of GdTMSi (TM = Mn, Cr) intermetallic compounds

The ternary intermetallic compounds GdTMSi (TM = Cr, Mn) attract the attention of researchers because of variability of physical and chemical properties and potential for practical use. They crystallize in the CeFeSi-type tetragonal structure P4/nmm. Several magnetic transitions were found in GdMnSi at temperatures 50, 275, and 310-325 K [1]. There are no data on synthesis and study of GdCrSi reported. In this work, the calculations of the electronic structure were performed in Quantum ESPRESSO computer package [2] using the exchange-correlation potential in the generalized gradient correction (GGA) approximation of the PBE version [3]. The GGA+U method was used, adjusted for the strong electron-electron interaction. For Gd ions, the values of spin polarization obtained as a result of self-consistent calculations correspond to a magnetic moment of 7.2 μB per Gd ion. The Si ions are non-magnetic, while the magnetic moment of the Cr and Mn ions is approximately 2-4 µB, which significantly reduces the total magnetic moment in the case of Mn. For the GdCrSi compounds, the ordering is antiferromagnetic in the transition metal sublattice. In the calculations for GdCrSi, the value of the total magnetic moment for GdCrSi per formula unit was equal to 4.86 µB due to the value of the magnetic moment of the Gd ion. At the same time, the transition metal ions Cr in this compound have a magnetic moment of 2.7 µB. The calculations have shown that the GdTMSi compounds have differences not only in the magnetic properties, but also in the electronic structure. The electronic states near the Fermi level are determined primarily by the 3d states of the TM ions. In the studied intermetallics, we found that they are very different depending on the TM type, which indicates a difference in transport properties, and makes the GdTMSi intermetallics promising for use in microelectronic applications. This study was supported by the grant of Russian Science Foundation No 18-72-10098, https://rscf.ru/en/project/18-72-10098/.