Magnetism, electron transport and effect of disorder in CoFeCrAl

• Published in: Journal of physics. D, Applied physics Vol. 48; no. 24; pp. 245002 - 6
• Main Authors: Kharel, P, Zhang, W, Skomski, R, Valloppilly, S, Huh, Y, Fuglsby, R, Gilbert, S, Sellmyer, D J
• Format: Journal Article
• Language: English
• Published: United Kingdom IOP Publishing 24.06.2015
• Subjects: Curie temperature; disorder; Electrical resistivity; Electronics; Heusler alloys; Magnetic properties; Mathematical models; Saturation (magnetic); spin gapless semiconductor; Temperature dependence; Vacuum annealing
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/48/24/245002

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 µB/f.u. and 2.1 µB/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  cm at 5 K to about 820 µ  cm at 250 K, with dρ/dT 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.