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Title: Phenomenology of giant magnetic-field-induced strain in ferromagnetic shape-memory materials (invited)

Abstract

Ferromagnetic shape-memory alloys have recently emerged as a new class of active materials showing very large magnetic-field-induced extensional strains. Recently, a single crystal of a tetragonally distorted Heusler alloy in the NiMnGa system has shown a 5% shear strain at room temperature in a field of 4 kOe. The magnetic and crystallographic aspects of the twin-boundary motion responsible for this effect are described. Ferromagnetic shape-memory alloys strain by virtue of the motion of the boundaries separating adjacent twin variants. The twin-boundary motion is driven by the Zeeman energy difference between the adjacent twins due to their nearly orthogonal magnetic easy axes and large magnetocrystalline anisotropy. The twin boundary constitutes a nearly 90 degree sign domain wall. Essentially, twin-boundary motion shorts out the more difficult magnetization rotation process. The field and stress dependence of the strain are reasonably well accounted for by minimization of a simple free energy expression including Zeeman energy, magnetic anisotropy energy, internal elastic energy, and external stress. Models indicate the limits to the magnitude of the field-induced strain and point to the material parameters that make the effect possible. The field-induced strain in ferromagnetic shape-memory alloys is contrasted with the more familiar phenomenon of magnetostriction. (c) 2000more » American Institute of Physics.« less

Authors:
 [1];  [1];  [1];  [1];  [1]
  1. Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
Publication Date:
OSTI Identifier:
20216205
Resource Type:
Journal Article
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 87; Journal Issue: 9; Other Information: PBD: 1 May 2000; Journal ID: ISSN 0021-8979
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; SHAPE MEMORY EFFECT; STRAINS; HEUSLER ALLOYS; NICKEL ALLOYS; MANGANESE ALLOYS; GALLIUM ALLOYS; TWINNING; DOMAIN STRUCTURE; FERROMAGNETIC MATERIALS; ZEEMAN EFFECT; THEORETICAL DATA

Citation Formats

O'Handley, R. C., Murray, S. J., Marioni, M., Nembach, H., and Allen, S. M. Phenomenology of giant magnetic-field-induced strain in ferromagnetic shape-memory materials (invited). United States: N. p., 2000. Web. doi:10.1063/1.373136.
O'Handley, R. C., Murray, S. J., Marioni, M., Nembach, H., & Allen, S. M. Phenomenology of giant magnetic-field-induced strain in ferromagnetic shape-memory materials (invited). United States. doi:10.1063/1.373136.
O'Handley, R. C., Murray, S. J., Marioni, M., Nembach, H., and Allen, S. M. Mon . "Phenomenology of giant magnetic-field-induced strain in ferromagnetic shape-memory materials (invited)". United States. doi:10.1063/1.373136.
@article{osti_20216205,
title = {Phenomenology of giant magnetic-field-induced strain in ferromagnetic shape-memory materials (invited)},
author = {O'Handley, R. C. and Murray, S. J. and Marioni, M. and Nembach, H. and Allen, S. M.},
abstractNote = {Ferromagnetic shape-memory alloys have recently emerged as a new class of active materials showing very large magnetic-field-induced extensional strains. Recently, a single crystal of a tetragonally distorted Heusler alloy in the NiMnGa system has shown a 5% shear strain at room temperature in a field of 4 kOe. The magnetic and crystallographic aspects of the twin-boundary motion responsible for this effect are described. Ferromagnetic shape-memory alloys strain by virtue of the motion of the boundaries separating adjacent twin variants. The twin-boundary motion is driven by the Zeeman energy difference between the adjacent twins due to their nearly orthogonal magnetic easy axes and large magnetocrystalline anisotropy. The twin boundary constitutes a nearly 90 degree sign domain wall. Essentially, twin-boundary motion shorts out the more difficult magnetization rotation process. The field and stress dependence of the strain are reasonably well accounted for by minimization of a simple free energy expression including Zeeman energy, magnetic anisotropy energy, internal elastic energy, and external stress. Models indicate the limits to the magnitude of the field-induced strain and point to the material parameters that make the effect possible. The field-induced strain in ferromagnetic shape-memory alloys is contrasted with the more familiar phenomenon of magnetostriction. (c) 2000 American Institute of Physics.},
doi = {10.1063/1.373136},
journal = {Journal of Applied Physics},
issn = {0021-8979},
number = 9,
volume = 87,
place = {United States},
year = {2000},
month = {5}
}