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Title: Growth, electrical, structural, and magnetic properties of half-Heusler CoT i 1 - x F e x Sb

Epitaxial thin films of the substitutionally alloyed half-Heusler series CoTi 1-xFe xSb were grown by molecular beam epitaxy on InAlAs/InP(001) substrates for concentrations 0.0 ≤ x ≤ 1.0. The influence of Fe on the structural, electronic, and magnetic properties was studied and compared to that expected from density functional theory. The films are epitaxial and single crystalline, as measured by reflection high-energy electron diffraction and X-ray diffraction. Using in-situ X-ray photoelectron spectroscopy, only small changes in the valence band are detected for x ≤ 0.5. For films with x ≥ 0.05, ferromagnetism is observed in SQUID magnetometry with a saturation magnetization that scales linearly with Fe content. A dramatic decrease in the magnetic moment per formula unit occurs when the Fe is substitutionally alloyed on the Co site indicating a strong dependence on the magnetic moment with site occupancy. A crossover from both in-plane and out-of-plane magnetic moments to only in-plane moment occurs for higher concentrations of Fe. Ferromagnetic resonance indicates a transition from weak to strong interaction with a reduction in inhomogeneous broadening as Fe content is increased. Temperature-dependent transport reveals a semiconductor to metal transition with thermally activated behavior for x ≤ 0.5. Anomalous Hall effect and largemore » negative magnetoresistance (up to -18.5% at 100 kOe for x=0.3) are observed for higher Fe content films. Evidence of superparamagnetism for x=0.3 and x=0.2 suggests for moderate levels of Fe, demixing of the CoTi 1-xFe xSb films into Fe rich and Fe deficient regions may be present. Atom probe tomography is used to examine the Fe distribution in a x=0.3 film. Finally, statistical analysis reveals a nonhomogeneous distribution of Fe atoms throughout the film, which is used to explain the observed magnetic and electrical behavior.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [1] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [5] ;  [8]
  1. Univ. of California, Santa Barbara, CA (United States). Materials Dept.
  2. Univ. of Delaware, Newark, DE (United States). Dept. of Physics and Astronomy
  3. Univ. of California, Santa Barbara, CA (United States). Dept. of Electrical and Computer Engineering
  4. Univ. of California, Santa Barbara, CA (United States). Dept. of Physics
  5. Gebze Technical Univ., Kocaeli (Turkey)
  6. South Dakota School of Mines and Technology, Rapid City, SD (United States). Dept. of Physics
  7. Univ. of Delaware, Newark, DE (United States). Dept. of Physics and Astronomy; Univ. of Delaware, Newark, DE (United States). Dept. of Materials Science & Engineering
  8. Univ. of California, Santa Barbara, CA (United States). Materials Dept.; Univ. of California, Santa Barbara, CA (United States). Dept. of Electrical and Computer Engineering
Publication Date:
Grant/Contract Number:
SC0014388; ACI-1053575; 1144085
Type:
Accepted Manuscript
Journal Name:
Physical Review Materials
Additional Journal Information:
Journal Volume: 2; Journal Issue: 1; Journal ID: ISSN 2475-9953
Publisher:
American Physical Society (APS)
Research Org:
Univ. of California, Santa Barabara, CA (United States); Univ. of Delaware, Newark, DE (United States)
Sponsoring Org:
USDOE Office of Science (SC); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Heusler alloys; Ferromagnetism; Half Heusler; Anamolous Hall effect; Growth; Magnetoresistance; Magnetotransport; Superparamagnetism
OSTI Identifier:
1416742
Alternate Identifier(s):
OSTI ID: 1416837

Harrington, S. D., Rice, A. D., Brown-Heft, T. L., Bonef, B., Sharan, A., McFadden, A. P., Logan, J. A., Pendharkar, M., Feldman, M. M., Mercan, O., Petukhov, A. G., Janotti, A., Colakerol Arslan, L., and Palmstrøm, C. J.. Growth, electrical, structural, and magnetic properties of half-Heusler CoTi1-xFexSb. United States: N. p., Web. doi:10.1103/PhysRevMaterials.2.014406.
Harrington, S. D., Rice, A. D., Brown-Heft, T. L., Bonef, B., Sharan, A., McFadden, A. P., Logan, J. A., Pendharkar, M., Feldman, M. M., Mercan, O., Petukhov, A. G., Janotti, A., Colakerol Arslan, L., & Palmstrøm, C. J.. Growth, electrical, structural, and magnetic properties of half-Heusler CoTi1-xFexSb. United States. doi:10.1103/PhysRevMaterials.2.014406.
Harrington, S. D., Rice, A. D., Brown-Heft, T. L., Bonef, B., Sharan, A., McFadden, A. P., Logan, J. A., Pendharkar, M., Feldman, M. M., Mercan, O., Petukhov, A. G., Janotti, A., Colakerol Arslan, L., and Palmstrøm, C. J.. 2018. "Growth, electrical, structural, and magnetic properties of half-Heusler CoTi1-xFexSb". United States. doi:10.1103/PhysRevMaterials.2.014406.
@article{osti_1416742,
title = {Growth, electrical, structural, and magnetic properties of half-Heusler CoTi1-xFexSb},
author = {Harrington, S. D. and Rice, A. D. and Brown-Heft, T. L. and Bonef, B. and Sharan, A. and McFadden, A. P. and Logan, J. A. and Pendharkar, M. and Feldman, M. M. and Mercan, O. and Petukhov, A. G. and Janotti, A. and Colakerol Arslan, L. and Palmstrøm, C. J.},
abstractNote = {Epitaxial thin films of the substitutionally alloyed half-Heusler series CoTi1-xFexSb were grown by molecular beam epitaxy on InAlAs/InP(001) substrates for concentrations 0.0 ≤ x ≤ 1.0. The influence of Fe on the structural, electronic, and magnetic properties was studied and compared to that expected from density functional theory. The films are epitaxial and single crystalline, as measured by reflection high-energy electron diffraction and X-ray diffraction. Using in-situ X-ray photoelectron spectroscopy, only small changes in the valence band are detected for x ≤ 0.5. For films with x ≥ 0.05, ferromagnetism is observed in SQUID magnetometry with a saturation magnetization that scales linearly with Fe content. A dramatic decrease in the magnetic moment per formula unit occurs when the Fe is substitutionally alloyed on the Co site indicating a strong dependence on the magnetic moment with site occupancy. A crossover from both in-plane and out-of-plane magnetic moments to only in-plane moment occurs for higher concentrations of Fe. Ferromagnetic resonance indicates a transition from weak to strong interaction with a reduction in inhomogeneous broadening as Fe content is increased. Temperature-dependent transport reveals a semiconductor to metal transition with thermally activated behavior for x ≤ 0.5. Anomalous Hall effect and large negative magnetoresistance (up to -18.5% at 100 kOe for x=0.3) are observed for higher Fe content films. Evidence of superparamagnetism for x=0.3 and x=0.2 suggests for moderate levels of Fe, demixing of the CoTi1-xFexSb films into Fe rich and Fe deficient regions may be present. Atom probe tomography is used to examine the Fe distribution in a x=0.3 film. Finally, statistical analysis reveals a nonhomogeneous distribution of Fe atoms throughout the film, which is used to explain the observed magnetic and electrical behavior.},
doi = {10.1103/PhysRevMaterials.2.014406},
journal = {Physical Review Materials},
number = 1,
volume = 2,
place = {United States},
year = {2018},
month = {1}
}

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