Structural, Electronic, Optical and Magnetic Properties of Co2CrZ (Z= Al, Bi, Ge, Si) Heusler Compounds

Abstract

In this paper, we have studied the structural, electronic, optical and magnetic properties of Co₂CrZ (Z= Al, Bi, Ge, Si) compounds by using two different methods one is full potential linearized augmented plane wave (FP-LAPW) method as implemented in WIEN2k and second is pseudo potential method as implemented in Atomistic Tool Kit-Virtual NanoLab (ATK-VNL). The respective band gaps in their minority-spin of Co₂CrZ (Z= Al, Bi, Ge, Si) are 0.696, 0.257, 0.602 and 0.858 eV near the Fermi level, which is implemented in WIEN2k code and showing 100% spin polarization. Further, these compounds have been found to be perfectly half-metallic ferromagnetic (HMF). However, above mentioned compounds shows zero band gaps in ATK-VNL code. The calculated magnetic moment of these compounds Co₂CrZ (Z= Al, Bi, Ge, Si) are 3.06, 4.99, 3.99 and 3.99µ_B respectively in FP-LAPW method. However, the respective magnetic moment of these compounds is found to be 3.14, 5.08, 4.11 and 4.08µ_B in ATK-VNL code. Optical properties play an important role to understand the nature of material whether it can be used as optoelectronics device. From the optical Spectra, complex dielectric functions calculated values are 312.370 and 141.991, 299.812 and 111.368, 288.127 and 106.342, 290.688 and 99.095 for the compounds Co₂CrZ (Z= Al, Bi, Ge, Si) respectively by using WIEN2k. The maximum energy loss is observed between 11.4 to 13eV for above these compounds. The refractive index values for the compounds Co₂CrZ (Z= Al, Bi, Ge, Si) are observed as 18.104, 17.602, 17.252 and 17.289 respectively. In the optical conductivity spectrum a sharp peak is observed at 1.6 - 2.3eV.