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Title: Half-metallicity in highly L2 1-ordered CoFeCrAl thin films

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 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 390 K, and a net moment of 2 μ B 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 × 10 18 cm -3 and 33 cm 2/V s, respectively. In contrast to the well-investigated Heusler alloys such as Co 2(Cr 1-xFe x)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 themore » context of spin electronics.« less

Authors:
 [1];  [2];  [3];  [3];  [4];  [4]; ORCiD logo [4];  [5];  [5];  [1];  [1]
  1. Univ. of Nebraska, Lincoln, NE (United States). Dept. of Physics and Astronomy; Univ. of Nebraska, Lincoln, NE (United States). Nebraska Center for Materials and Nanoscience
  2. Univ. of Nebraska, Lincoln, NE (United States). Nebraska Center for Materials and Nanoscience; South Dakota State Univ., Brookings, SD (United States). Dept. of Physics
  3. Univ. of Nebraska, Lincoln, NE (United States). Nebraska Center for Materials and Nanoscience
  4. Arizona State Univ., Tempe, AZ (United States). Dept. of Physics
  5. Indian Inst. of Technology, Mandi, Himachal Pradesh (India). School of Basic Sciences
Publication Date:
Research Org.:
Univ. of Nebraska, Lincoln, NE (United States); Energy Frontier Research Centers (EFRC) (United States). Spins and Heat in Nanoscale Electronic Systems (SHINES)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
OSTI Identifier:
1465777
Alternate Identifier(s):
OSTI ID: 1328224
Grant/Contract Number:  
FG02-04ER46152; SC0012670
Resource Type:
Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 109; Journal Issue: 14; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English

Citation Formats

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. Half-metallicity in highly L21-ordered CoFeCrAl thin films. United States: N. p., 2016. Web. doi:10.1063/1.4964464.
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., & Sellmyer, D. J. Half-metallicity in highly L21-ordered CoFeCrAl thin films. United States. doi:10.1063/1.4964464.
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. Mon . "Half-metallicity in highly L21-ordered CoFeCrAl thin films". United States. doi:10.1063/1.4964464. https://www.osti.gov/servlets/purl/1465777.
@article{osti_1465777,
title = {Half-metallicity in highly L21-ordered CoFeCrAl thin films},
author = {Jin, Y. and Kharel, P. and Valloppilly, S. R. and Li, X. -Z. and Kim, D. R. and Zhao, G. J. and Chen, T. Y. and Choudhary, R. and Kashyap, A. and Skomski, R. and Sellmyer, D. J.},
abstractNote = {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.},
doi = {10.1063/1.4964464},
journal = {Applied Physics Letters},
number = 14,
volume = 109,
place = {United States},
year = {2016},
month = {10}
}

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