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Title: Magnetism and electronic structure of CoFeCrX (X = Si, Ge) Heusler alloys

Abstract

The structural, electronic, and magnetic properties of CoFeCrX (X = Si, Ge) Heusler alloys have been investigated. Experimentally, the alloys were synthesized in the cubic L2{sub 1} structure with small disorder. The cubic phase of CoFeCrSi was found to be highly stable against heat treatment, but CoFeCrGe disintegrated into other new compounds when the temperature reached 402 °C (675 K). Although the first-principle calculation predicted the possibility of tetragonal phase in CoFeCrGe, the tetragonal phase could not be stabilized experimentally. Both CoFeCrSi and CoFeCrGe compounds showed ferrimagnetic spin order at room temperature and have Curie temperatures (T{sub C}) significantly above room temperature. The measured T{sub C} for CoFeCrSi is 790 K but that of CoFeCrGe could not be measured due to its dissociation into new compounds at 675 K. The saturation magnetizations of CoFeCrSi and CoFeCrGe are 2.82 μ{sub B}/f.u. and 2.78 μ{sub B}/f.u., respectively, which are close to the theoretically predicted value of 3 μ{sub B}/f.u. for their half-metallic phases. The calculated band gaps for CoFeCrSi and CoFeCrGe are, respectively, 1 eV and 0.5 eV. These materials have potential for spintronic device applications, as they exhibit half-metallic electronic structures with large band gaps, and Curie temperatures significantly above room temperature.

Authors:
;  [1];  [2];  [3]; ; ;  [4];  [5];  [6]; ; ;  [2];  [2];  [7]; ;  [1];  [3]
  1. Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588 (United States)
  2. Department of Physics, South Dakota State University, Brookings, South Dakota 57007 (United States)
  3. (United States)
  4. Department of Physics, University of Northern Iowa, Cedar Falls, Iowa 50614 (United States)
  5. Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588 (United States)
  6. Department of Chemistry and Biochemistry, University of Northern Iowa, Cedar Falls, Iowa 50614 (United States)
  7. (China)
Publication Date:
OSTI Identifier:
22597689
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 120; Journal Issue: 5; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CURIE POINT; DISSOCIATION; ELECTRONIC STRUCTURE; HEAT; HEAT TREATMENTS; HEUSLER ALLOYS; MAGNETIC PROPERTIES; MAGNETISM; MAGNETIZATION; SATURATION; SPIN; TEMPERATURE RANGE 0273-0400 K; TEMPERATURE RANGE 0400-1000 K

Citation Formats

Jin, Y., O'Connell, A., Kharel, P., E-mail: parashu.kharel@sdstate.edu, Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588, Lukashev, P., E-mail: pavel.lukashev@uni.edu, Staten, B., Tutic, I., Valloppilly, S., Herran, J., Mitrakumar, M., Bhusal, B., Huh, Y., Yang, K., College of Mechanical and Electrical Engineering, Hohai University, Changzhou, Skomski, R., Sellmyer, D. J., and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588. Magnetism and electronic structure of CoFeCrX (X = Si, Ge) Heusler alloys. United States: N. p., 2016. Web. doi:10.1063/1.4960350.
Jin, Y., O'Connell, A., Kharel, P., E-mail: parashu.kharel@sdstate.edu, Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588, Lukashev, P., E-mail: pavel.lukashev@uni.edu, Staten, B., Tutic, I., Valloppilly, S., Herran, J., Mitrakumar, M., Bhusal, B., Huh, Y., Yang, K., College of Mechanical and Electrical Engineering, Hohai University, Changzhou, Skomski, R., Sellmyer, D. J., & Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588. Magnetism and electronic structure of CoFeCrX (X = Si, Ge) Heusler alloys. United States. doi:10.1063/1.4960350.
Jin, Y., O'Connell, A., Kharel, P., E-mail: parashu.kharel@sdstate.edu, Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588, Lukashev, P., E-mail: pavel.lukashev@uni.edu, Staten, B., Tutic, I., Valloppilly, S., Herran, J., Mitrakumar, M., Bhusal, B., Huh, Y., Yang, K., College of Mechanical and Electrical Engineering, Hohai University, Changzhou, Skomski, R., Sellmyer, D. J., and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588. Sun . "Magnetism and electronic structure of CoFeCrX (X = Si, Ge) Heusler alloys". United States. doi:10.1063/1.4960350.
@article{osti_22597689,
title = {Magnetism and electronic structure of CoFeCrX (X = Si, Ge) Heusler alloys},
author = {Jin, Y. and O'Connell, A. and Kharel, P., E-mail: parashu.kharel@sdstate.edu and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588 and Lukashev, P., E-mail: pavel.lukashev@uni.edu and Staten, B. and Tutic, I. and Valloppilly, S. and Herran, J. and Mitrakumar, M. and Bhusal, B. and Huh, Y. and Yang, K. and College of Mechanical and Electrical Engineering, Hohai University, Changzhou and Skomski, R. and Sellmyer, D. J. and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588},
abstractNote = {The structural, electronic, and magnetic properties of CoFeCrX (X = Si, Ge) Heusler alloys have been investigated. Experimentally, the alloys were synthesized in the cubic L2{sub 1} structure with small disorder. The cubic phase of CoFeCrSi was found to be highly stable against heat treatment, but CoFeCrGe disintegrated into other new compounds when the temperature reached 402 °C (675 K). Although the first-principle calculation predicted the possibility of tetragonal phase in CoFeCrGe, the tetragonal phase could not be stabilized experimentally. Both CoFeCrSi and CoFeCrGe compounds showed ferrimagnetic spin order at room temperature and have Curie temperatures (T{sub C}) significantly above room temperature. The measured T{sub C} for CoFeCrSi is 790 K but that of CoFeCrGe could not be measured due to its dissociation into new compounds at 675 K. The saturation magnetizations of CoFeCrSi and CoFeCrGe are 2.82 μ{sub B}/f.u. and 2.78 μ{sub B}/f.u., respectively, which are close to the theoretically predicted value of 3 μ{sub B}/f.u. for their half-metallic phases. The calculated band gaps for CoFeCrSi and CoFeCrGe are, respectively, 1 eV and 0.5 eV. These materials have potential for spintronic device applications, as they exhibit half-metallic electronic structures with large band gaps, and Curie temperatures significantly above room temperature.},
doi = {10.1063/1.4960350},
journal = {Journal of Applied Physics},
number = 5,
volume = 120,
place = {United States},
year = {Sun Aug 07 00:00:00 EDT 2016},
month = {Sun Aug 07 00:00:00 EDT 2016}
}