2013/11/08 by Denis Comtesse, Benjamin Geisler, Comtesse, Denis +10
Materials Science · Physics and Astronomy · #Advanced Thermoelectric Materials and Devices #Heusler alloys: electronic and magnetic properties #Magnetic properties of thin films #cond-mat.mtrl-sci
paper · pdf · doi:10.48550/arxiv.1311.1950
arxiv created 2013/11/08 · arxiv updated 2013/11/11
The electronic and magnetic bulk properties of half-metallic Heusler alloys such as Co2FeSi, Co2FeAl, Co2MnSi and Co2MnAl are investigated by means of \em ab initio calculations in combination with Monte Carlo simulations. The electronic structure is analyzed using the plane wave code Quantum Espresso and magnetic exchange interactions are determined using the KKR method. From the magnetic exchange interactions the Curie temperature is obtained via Monte Carlo simulations. In addition, electronic transport properties of the trilayer systems consisting of two semi-infinite platinum leads and a Heusler layer in between are obtained from the fully relativistic KKR method by employing the Kubo-Greenwood formalism. The focus is on thermoelectric properties, namely the Seebeck effect and its spin dependence. It turns out that already thin Heusler layers provide highly polarized currents within the systems. This is attributed to the recovery of half-metallicity with increasing thickness. The absence of electronic states of the spin down electrons around the Fermi level suppresses the contribution of this spin channel to the total conductivity. This strongly influences the thermoelectric properties of such systems and results in polarized thermoelectric currents.