Electronic band structure, mechanical and thermodynamic properties of Erbium chalcogenides ErX (X = S, Se and Te): A computational insight

Abstract

We have investigated the structural, electronic, magnetic, mechanical, and thermodynamic properties of Erbium chalcogenides, ErX (X = S, Se and Te) using a suitable density functional theory (DFT) approach. ErX compounds were found stable in NaCl-type structure and in the ferromagnetic phase. The electronic band structure diagrams showed metallic nature of the ErX compounds in both the majority and minority spin channels. Higher value of the bulk modulus for ErS showed high stiffness resistance as compare to other two members. The calculated total magnetic moments were found to be 2.18 μB, 2.17 μB, and 2.22 μB for ErS, ErSe and ErTe compounds, respectively. The major contribution in the magnetic moment was found due to f -electrons of Er. The elastic and mechanical properties have also been computed. The calculated values of bulk modulus to shear modulus (B/G) and Cauchy pressure indicated their brittle nature. As per the Zener anisotropy factor, these materials were also found to be elastically anisotropic. The thermodynamic constants including the bulk modulus, specific heat at constant volume, thermal expansion coefficient, entropy and Debye were calculated for ErX compounds for the first time.