Effects of Disorder on the Electronic Structure and Thermoelectric Properties of an Inverse Full-Heusler Mn<sub>2</sub>CoAl Alloy
Hezhang Li, Kei Hayashi, Yoshimi Nagashima, Shun Yoshioka, Jinfeng Dong, Jing‐Feng Li, Yuzuru Miyazaki
Abstract
We report a detailed analysis of the crystal structure, electronic structure, and thermoelectric (TE) properties of a stoichiometric Mn2CoAl inverse full-Heusler alloy, which has been predicted to be a spin-gapless semiconductor. To reveal the effects of disorder on TE properties (electrical conductivity and Seebeck coefficient), we prepared Mn2Co(Al1–xSix) (x = 0, 0.05, and 0.1) bulk samples by arc melting. The crystal structure analysis indicates that antisite defects exist in the prepared samples. From the measurements of the electrical conductivity and Seebeck coefficient, it is demonstrated that the prepared Mn2CoAl alloy is not a spin-gapless semiconductor but a half-metal. A relation between the crystal structure and TE properties is discussed based on the calculation of the electronic structure considering the antisite defects in Mn2CoAl.