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Title: Direct evidence for the source of reported magnetic behavior in “CoTe”

Abstract

In order to unambiguously identify the source of magnetism reported in recent studies of the Co-Te system, two sets of high-quality, epitaxial CoTe x films (thickness ≈ 300 nm) were prepared by pulse laser deposition (PLD). X-ray diffraction (XRD) shows that all of the films are epitaxial along the [001] direction and have the hexagonal NiAs structure. There is no indication of any second phase metallic Co peaks (either fcc or hcp) in the XRD patterns. The two sets of CoTex films were grown on various substrates with PLD targets having Co:Te in the atomic ratio of 50:50 and 35:65. From the measured lattice parameters c = 5.396 Å for the former and c = 5.402 Å for the latter, the compositions CoTe 1.71 (63.1% Te) and CoTe 1.76 (63.8% Te), respectively, are assigned to the principal phase. Although XRD shows no trace of metallic Co second phase, the magnetic measurements do show a ferromagnetic contribution for both sets of films with the saturation magnetization values for the CoTe 1.71 films being approximately four times the values for the CoTe 1.76 films. 59Co spin-echo nuclear magnetic resonance (NMR) clearly shows the existence of metallic Co inclusions in the films. Inmore » conclusion, the source of weak ferromagnetism reported in several recent studies is due to the presence of metallic Co, since the stoichiometric composition “CoTe” does not exist.« less

Authors:
ORCiD logo [1];  [1];  [1];  [1];  [1]
  1. Univ. of Connecticut, Storrs, CT (United States)
Publication Date:
Research Org.:
Univ. of Connecticut, Storrs, CT (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1499682
Alternate Identifier(s):
OSTI ID: 1414605
Grant/Contract Number:  
FG02-00ER45801
Resource Type:
Accepted Manuscript
Journal Name:
AIP Advances
Additional Journal Information:
Journal Volume: 7; Journal Issue: 12; Journal ID: ISSN 2158-3226
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Zhang, Zhiwei, Hines, William A., Budnick, Joseph I., Perry, David M., and Wells, Barrett O. Direct evidence for the source of reported magnetic behavior in “CoTe”. United States: N. p., 2017. Web. doi:10.1063/1.4997161.
Zhang, Zhiwei, Hines, William A., Budnick, Joseph I., Perry, David M., & Wells, Barrett O. Direct evidence for the source of reported magnetic behavior in “CoTe”. United States. doi:10.1063/1.4997161.
Zhang, Zhiwei, Hines, William A., Budnick, Joseph I., Perry, David M., and Wells, Barrett O. Fri . "Direct evidence for the source of reported magnetic behavior in “CoTe”". United States. doi:10.1063/1.4997161. https://www.osti.gov/servlets/purl/1499682.
@article{osti_1499682,
title = {Direct evidence for the source of reported magnetic behavior in “CoTe”},
author = {Zhang, Zhiwei and Hines, William A. and Budnick, Joseph I. and Perry, David M. and Wells, Barrett O.},
abstractNote = {In order to unambiguously identify the source of magnetism reported in recent studies of the Co-Te system, two sets of high-quality, epitaxial CoTex films (thickness ≈ 300 nm) were prepared by pulse laser deposition (PLD). X-ray diffraction (XRD) shows that all of the films are epitaxial along the [001] direction and have the hexagonal NiAs structure. There is no indication of any second phase metallic Co peaks (either fcc or hcp) in the XRD patterns. The two sets of CoTex films were grown on various substrates with PLD targets having Co:Te in the atomic ratio of 50:50 and 35:65. From the measured lattice parameters c = 5.396 Å for the former and c = 5.402 Å for the latter, the compositions CoTe1.71 (63.1% Te) and CoTe1.76 (63.8% Te), respectively, are assigned to the principal phase. Although XRD shows no trace of metallic Co second phase, the magnetic measurements do show a ferromagnetic contribution for both sets of films with the saturation magnetization values for the CoTe1.71 films being approximately four times the values for the CoTe1.76 films. 59Co spin-echo nuclear magnetic resonance (NMR) clearly shows the existence of metallic Co inclusions in the films. In conclusion, the source of weak ferromagnetism reported in several recent studies is due to the presence of metallic Co, since the stoichiometric composition “CoTe” does not exist.},
doi = {10.1063/1.4997161},
journal = {AIP Advances},
number = 12,
volume = 7,
place = {United States},
year = {2017},
month = {12}
}

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