Magnetism, electron transport and effect of disorder in CoFeCrAl. (19th May 2015)

• Record Type: Journal Article
• Authors: Kharel, P; Zhang, W; Skomski, R; Valloppilly, S; Huh, Y; Fuglsby, R; Gilbert, S; Sellmyer, D J
• Is Part Of: Journal of physics. Volume 48:Number 24(2015)
• Publication Date: 2015-05-19
• Subjects: spin gapless semiconductor -- Heusler alloys -- disorder; Physics -- Periodicals; 530
• DOI: 10.1088/0022-3727/48/24/245002
• Languages: English
• ISSNs: 0022-3727

Abstract

Abstract: Structural, electronic, and magnetic properties of a Heusler-type CoFeCrAl alloy have been investigated experimentally and by model calculations, with a focus on the alloy's spin-gapless semiconductivity. The as-quenched samples are ferrimagnetic at room temperature with a Curie temperature of about 456 K, which increases to 540 K after vacuum annealing at 600 °C for 2 h. The saturation magnetizations of the as-quenched and 600 °C-annealed samples are 1.9 µ B /f.u. and 2.1 µ B /f.u., respectively, which are very close to the value predicted by the Slater–Pauling curve. The resistivity shows a nearly linear decrease with increasing temperature, from about 930 µ Ω cm at 5 K to about 820 µ Ω cm at 250 K, with d ρ/ d T of about −5 × 10 −7 Ω cm K −1 . We explain this high resistivity and its temperature dependence as imperfect spin-gapless semiconducting behavior, with a negative band-gap parameter of 0.2 eV.