The Structural, Electronic, Magnetic, and Optical Properties of Mn2ZrGa1−x Ge x Heusler Alloys: First-Principles Calculations

Abstract

The structural, electronic, magnetic, and optical properties of Mn-based Heusler Mn2ZrGa1−x Ge x (x = 0, 0.25, 0.5, 0.75, and 1) alloys are calculated by first-principles full-potential linearized augmented plane wave plus local orbital (FP-LAPW+lo) method. It is found that Mn2ZrGa1−x Ge x alloys are half-metallic ferrimagnetic and their magnetic moments are in good agreement with the Slater–Pauling relationship. The calculations reveal that all alloys have a pseudo-gap in the majority-spin channel except for x = 0.75 and x = 1 which have a real gap in the majority-spin channel. The spin polarization is quite large for whole series, and it reaches to a value of 100% for x = 0.75 and x = 1. Our calculated results clearly show that with the Ge substitution, the lattice parameter linearly decreases while the bulk modulus increases. Moreover, the calculated formation energies confirm that these alloys are stable chemically. The optical properties, including the real and imaginary parts of the dielectric function, reflectivity, and absorption spectra, were also investigated. The results show that the dominant behavior, at energy below 1 eV, is due to interactions of free electrons in the system. The increment of Ge concentration leads to an increase in the plasma frequency of metallic spin channel.