DFT analysis of the structural, electronic, magnetic and thermoelectric properties of X2NbI6 (X= Ga, In), vacancy-ordered double perovskites

Abstract

First-principles calculations based on density functional theory and classical Boltzmann theory were used to study the structural, electronic, magnetic, and spin-dependent thermoelectric characteristics of the X2NbI6 (X = Ga, In) vacancy-ordered perovskites. By calculating their tolerance factors, it was confirmed that these compounds exhibit cubic phase stability. From volume optimization procedure, it was revealed that they are ferromagnetic. Additionally, the negative formation energies suggest that a thermodynamic stable form of X 2 NbI 6 might be produced. The structural parameters, lattice constant and bulk modulus was analyzed to increase with replacement of In instead of Ga at X site. The electronic properties and integral values of total magnetic moments demonstrated the half metallic nature. The ferromagnetic nature and 100 % spin polarizability revealed the advantage of X2NbI6 for usage in the spintronic industry. Their effective use as thermoelectric materials in spin Seebeck effect was demonstrated by the spindependent thermoelectric properties.