Mechanical, thermal, electronic, and magnetic properties of Ca0.75Er0.25S alloy from a DFT approach: A promising material for spintronic applications

Abstract

This paper presents a systematic study of the calculated mechanical properties, electronic structures and magnetic moments of dilute magnetic semiconductor Ca1−xErxS (x = 25 %) using the density functional theory (DFT)-based the full potential linear augmented plane-wave (FP-LAPW) method. The exchange and correlation potential is treated by the generalized gradient approximation GGA-PBE frameworks, which are utilized to characterize the structural and elastic properties of Ca1−xErxS. Moreover, the GGA-PBE +U and mBJ-PBE+U were also applied for the electronic and magnetic properties. To understand magnetic ground state the energy difference in ferromagnetic (FM) and anti-ferromagnetic (AFM) configurations was calculated. The calculated band structure improves when GGA-PBE+U and the modified Becke-Johnson approach (mBJ-PBE+U) methods are employed. The electronic structure analysis reveals that GGA-PBE predicts Ca1−xErxS ternary alloy to be metallic while GGA-PBE +U and mBJ-PBE+U predicts it to be half metallic ferromagnetic with 100 % spin-polarization at the Fermi level, with magnetic moment of 2 μB per formula unit and a band gap 1.90 and 2.40 eV, respectively. Our results indicate that identical magnetic ground states are obtained GGA-PBE +U and mBJ-PBE+U and the magnetic moment mainly arises from 4 f of Erbium (Er). To our knowledge, this is the first time that the physical properties of Ca0.75Er0.25S have been reported, and with consequence the present results can provide the data support for experimental and other theoretical investigations.