1. Half-metallic in highly L21-ordered CoFeCrAl thin films.
- Author
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Jin, Y., Kharel, P., Valloppilly, S. R., Li, X.-Z., Kim, D. R., Zhao, G. J., Chen, T. Y., Choudhary, R., Kashyap, A., Skomski, R., and Sellmyer, D. J.
- Subjects
COBALT compounds ,THIN films ,ELECTRON transport ,MAGNETISM ,SINGLE crystals ,EPITAXY - Abstract
The structural, magnetic, and electron-transport properties of Heusler-ordered CoFeCrAl thin films are investigated experimentally and theoretically. The films, sputtered onto MgO and having thicknesses of about 100nm, exhibit virtually perfect single-crystalline epitaxy and a high degree of L2
1 chemical order. X-ray diffraction and transmission-electron microscopy show that the structure of the films is essentially of the L21 Heusler type. The films are ferrimagnetic, with a Curie temperature of about 390K, and a net moment of 2 μB per formula unit. The room temperature resistivity is 175 μΩ; the carrier concentration and mobility determined from the low temperature (5 K) measurement are 1.2 x 1018 cm-3 and 33 cm²/Vs, respectively. In contrast to the well-investigated Heusler alloys such as Co2 (Cr1-x Fex )Al, the CoFeCrAl system exhibits two main types of weak residual A2 disorder, namely, Co-Cr disorder and Fe-Cr disorder, the latter conserving half-metallicity. Point-contact Andreev reflection yields a lower bound for the spin polarization, 68% at 1.85K, but our structural and magnetization analyses suggest that the spin polarization at the Fermi level is probably higher than 90%. The high resistivity, spin polarization, and Curie temperature are encouraging in the context of spin electronics. [ABSTRACT FROM AUTHOR]- Published
- 2016
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