First-Principles Investigation on Thermoelectric and Vibrational Properties of Half-Metallic Ir2MnX (X = B, Al, Ga, In) Heusler Alloys

The electronic structure and thermoelectric (TE) properties of Ir (iridium)-based Heusler alloys (HAs), Ir2MnX (X = B, Al, Ga, In), are examined by density functional theory (DFT). To the best of the authors' knowledge, there are no findings on the TE properties of these Ir-based Heusler compounds. All of the Ir2MnX (X = B, Al, Ga, In) alloys are stabilized to ferromagnetic ordering. The calculated equilibrium lattice constants vary from other results by 0.2%. This study is focused on the half-metallic behavior of the alloys based on their electronic structure and finite magnetic moment, which defines their viability for spintronic applications and TE device fabrication. The computed spin magnetic moments follow the Slater-Pauling rule. Among the four investigated compounds, Ir2MnB is dynamically unstable. The transport property is explored using the semiclassical Boltzmann transport theory for structurally and dynamically stable alloys Ir2MnX (X = Al, Ga, In). At 800 K, the maximum power factor of the alloys is achieved at a hole concentration of -1.25 x 10(11) W m(-1) K-2 s(-1), indicating that these are promising TE application alloys.