Crossover of magnetoresistance in the zero-gap half-metallic Heusler alloy Fe₂CoSi

¹ State Key Laboratory for Magnetism, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences - Beijing 100190, PRC
² State Key Laboratory of Metastable Material Sciences and Technology, Yanshan University Qinhuangdao 066004, PRC
³ School of Physics, Shandong University - Jinan 250100, PRC

^(a) wenhong.wang@iphy.ac.cn

Received: 3 June 2013
Accepted: 3 August 2013

Abstract

This work reports on band structure and magneto-transport investigations of the inverse Heusler compound Fe₂CoSi. First-principles calculations show that Fe₂CoSi has a very peculiar band structure with a conducting property of the majority spin channel and a nearly zero bandgap in the minority spin channel. The prepared Fe₂CoSi sample possesses a highly ordered inverse Heusler structure with a magnetic moment of at 5 K and a high Curie temperature of 1038 K. With increasing temperature, a crossover from positive to negative magnetoresistance (MR) is observed. Combining this with the Hall effect measurements, we suggest that the intriguing crossover of the MR can be ascribed to the dominant spin carriers that change from the gapless minority spin channel to the majority spin channel at the Fermi level.