Half-metallicity in highly L21-ordered CoFeCrAl thin films

Y. Jin, P. Kharel, S. R. Valloppilly, X. Z. Li, D. R. Kim, G. J. Zhao, Tingyong Chen, R. Choudhary, A. Kashyap, R. Skomski, D. J. Sellmyer

Research output: Contribution to journalArticle

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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 100 nm, exhibit virtually perfect single-crystalline epitaxy and a high degree of L21 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 390 K, and a net moment of 2 μB per formula unit. The room temperature resistivity is 175 μΩ cm; the carrier concentration and mobility determined from the low temperature (5 K) measurement are 1.2 × 1018 cm-3 and 33 cm2/V s, respectively. In contrast to the well-investigated Heusler alloys such as Co2(Cr1-xFex)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 1.85 K, 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.

Original languageEnglish (US)
Article number142410
JournalApplied Physics Letters
Volume109
Issue number14
DOIs
StatePublished - Oct 3 2016

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metallicity
disorders
thin films
Curie temperature
polarization
electrical resistivity
epitaxy
transport properties
moments
magnetization
transmission electron microscopy
room temperature
electronics
diffraction
electrons
x rays

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

Cite this

Jin, Y., Kharel, P., Valloppilly, S. R., Li, X. Z., Kim, D. R., Zhao, G. J., ... Sellmyer, D. J. (2016). Half-metallicity in highly L21-ordered CoFeCrAl thin films. Applied Physics Letters, 109(14), [142410]. https://doi.org/10.1063/1.4964464

Half-metallicity in highly L21-ordered CoFeCrAl thin films. / Jin, Y.; Kharel, P.; Valloppilly, S. R.; Li, X. Z.; Kim, D. R.; Zhao, G. J.; Chen, Tingyong; Choudhary, R.; Kashyap, A.; Skomski, R.; Sellmyer, D. J.

In: Applied Physics Letters, Vol. 109, No. 14, 142410, 03.10.2016.

Research output: Contribution to journalArticle

Jin, Y, Kharel, P, Valloppilly, SR, Li, XZ, Kim, DR, Zhao, GJ, Chen, T, Choudhary, R, Kashyap, A, Skomski, R & Sellmyer, DJ 2016, 'Half-metallicity in highly L21-ordered CoFeCrAl thin films', Applied Physics Letters, vol. 109, no. 14, 142410. https://doi.org/10.1063/1.4964464
Jin Y, Kharel P, Valloppilly SR, Li XZ, Kim DR, Zhao GJ et al. Half-metallicity in highly L21-ordered CoFeCrAl thin films. Applied Physics Letters. 2016 Oct 3;109(14). 142410. https://doi.org/10.1063/1.4964464
Jin, Y. ; Kharel, P. ; Valloppilly, S. R. ; Li, X. Z. ; Kim, D. R. ; Zhao, G. J. ; Chen, Tingyong ; Choudhary, R. ; Kashyap, A. ; Skomski, R. ; Sellmyer, D. J. / Half-metallicity in highly L21-ordered CoFeCrAl thin films. In: Applied Physics Letters. 2016 ; Vol. 109, No. 14.
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