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Title: Magnetic-field-induced changes in superparamagnetic cluster dynamics in the martensitic phase of Ni 43Co 7Mn 40Sn 10

The off-stoichiometric Heusler alloys, such as Ni 50Mn 25+yX 25-y (X = Sn, In, Ga, etc.), have been extensively investigated using a variety of experimental techniques to probe their interesting and potentially useful magnetic properties. Recent 55Mn nuclear magnetic resonance (NMR) experiments, carried out largely in zero field (ZF) and making use of the large internal hyperfine field at the nuclear sites, have demonstrated the power of this approach in determining the ground state magnetic characteristics of these materials. In particular, the results reveal that distinct nanoscale ferromagnetic and antiferromagnetic phases coexist. A key parameter used in interpreting the NMR data is the transverse relaxation time T 2 which, inter alia, determines the NMR blocking temperature T$$N\atop{B}$$ MR of magnetic regions. The present experiments on a polycrystalline sample of a specific illustrative alloy, Ni 43Co 7Mn 40Sn 10, which has received considerable attention, show that the application of relatively small external fields, comparable to or greater than the local anisotropy field in the ferromagnetic cluster regions, produces dramatic changes in T 2 and hence T$$N\atop{B}$$ MR. The experimental findings are discussed using an extended version of a recently proposed nanocluster model for superparamagnetic systems. It is thus demonstrated that the field and temperature induced changes in T 2 provide a significant test of the model and lead to a notable advance in applying the NMR technique to the investigation of the magnetic properties of this type of alloy.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [2] ;  [3]
  1. Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. (MagLab)
  2. Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Aerospace Engineering and Mechanics
  3. Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemical Engineering and Materials Science
Publication Date:
Grant/Contract Number:
FG02-06ER46275; DMR-1157490; FA9550-12-1-0458; OISE-0967140; N00014-14-1-0714
Type:
Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 108; Journal Issue: 25; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)
Research Org:
Florida State Univ., Tallahassee, FL (United States); Univ. of Minnesota, Minneapolis, MN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF); US Air Force Office of Scientific Research (AFOSR); US Department of the Navy, Office of Naval Research (ONR)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ferromagnetism; magnetic phase transitions; spin echoes; alloy phase transitions; displacive phase transitions; nanomagnetism; nickel; cluster phase transitions; magnetic anisotropy
OSTI Identifier:
1467826
Alternate Identifier(s):
OSTI ID: 1259192

Kuhns, P. L., Hoch, M. J. R., Yuan, S., Reyes, A. P., Srivastava, V., James, R. D., and Leighton, C.. Magnetic-field-induced changes in superparamagnetic cluster dynamics in the martensitic phase of Ni43Co7Mn40Sn10. United States: N. p., Web. doi:10.1063/1.4954732.
Kuhns, P. L., Hoch, M. J. R., Yuan, S., Reyes, A. P., Srivastava, V., James, R. D., & Leighton, C.. Magnetic-field-induced changes in superparamagnetic cluster dynamics in the martensitic phase of Ni43Co7Mn40Sn10. United States. doi:10.1063/1.4954732.
Kuhns, P. L., Hoch, M. J. R., Yuan, S., Reyes, A. P., Srivastava, V., James, R. D., and Leighton, C.. 2016. "Magnetic-field-induced changes in superparamagnetic cluster dynamics in the martensitic phase of Ni43Co7Mn40Sn10". United States. doi:10.1063/1.4954732. https://www.osti.gov/servlets/purl/1467826.
@article{osti_1467826,
title = {Magnetic-field-induced changes in superparamagnetic cluster dynamics in the martensitic phase of Ni43Co7Mn40Sn10},
author = {Kuhns, P. L. and Hoch, M. J. R. and Yuan, S. and Reyes, A. P. and Srivastava, V. and James, R. D. and Leighton, C.},
abstractNote = {The off-stoichiometric Heusler alloys, such as Ni50Mn25+yX25-y (X = Sn, In, Ga, etc.), have been extensively investigated using a variety of experimental techniques to probe their interesting and potentially useful magnetic properties. Recent 55Mn nuclear magnetic resonance (NMR) experiments, carried out largely in zero field (ZF) and making use of the large internal hyperfine field at the nuclear sites, have demonstrated the power of this approach in determining the ground state magnetic characteristics of these materials. In particular, the results reveal that distinct nanoscale ferromagnetic and antiferromagnetic phases coexist. A key parameter used in interpreting the NMR data is the transverse relaxation time T2 which, inter alia, determines the NMR blocking temperature T$N\atop{B}$MR of magnetic regions. The present experiments on a polycrystalline sample of a specific illustrative alloy, Ni43Co7Mn40Sn10, which has received considerable attention, show that the application of relatively small external fields, comparable to or greater than the local anisotropy field in the ferromagnetic cluster regions, produces dramatic changes in T2 and hence T$N\atop{B}$MR. The experimental findings are discussed using an extended version of a recently proposed nanocluster model for superparamagnetic systems. It is thus demonstrated that the field and temperature induced changes in T2 provide a significant test of the model and lead to a notable advance in applying the NMR technique to the investigation of the magnetic properties of this type of alloy.},
doi = {10.1063/1.4954732},
journal = {Applied Physics Letters},
number = 25,
volume = 108,
place = {United States},
year = {2016},
month = {6}
}