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Title: Structural and magnetic phase transitions in Mn-Ni alloys

Abstract

When the Ni concentration exceeds about 18%, Mn-Ni alloys were expected to support two different noncollinear spin-density wave (SDW) phases. A triple-Q SDW with moments along the crystal diagonals was believed to appear in the fcc phase between T{sub N} and T{sub t}. Below T{sub t}, the fct phase with c>a was believed to contain a double-Q SDW with moments in the ab plane and at 45 degree sign angles from the crystal axes. Based on resistivity, neutron-scattering, and susceptibility measurements, we show that the structural and magnetic phase transitions in a Mn{sub 1-x}Ni{sub x} alloy with x{approx_equal}0.20 are actually distinct, with the structural phase transition at T{sub t}{approx_equal}250 K lying far above the magnetic transition at T{sub m}{approx_equal}125 K. A Hamiltonian which includes elastic, magnetoelastic, and noncollinearity energies is used to describe these two transitions. In the tetragonal phase between T{sub t} and T{sub m}, our model predicts a new SDW phase with moments tilted away from the crystal diagonals toward the ab plane. The energy gap in the spin-wave spectrum is predicted to change discontinuously at T{sub m}. (c) 2000 The American Physical Society.

Authors:
 [1];  [1];  [2];  [1];  [1];  [1];  [3];  [1]
  1. Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6032 (United States)
  2. Department of Physics, University of California, San Diego, California 92093 (United States)
  3. (United States)
Publication Date:
OSTI Identifier:
20216415
Resource Type:
Journal Article
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 61; Journal Issue: 18; Other Information: PBD: 1 May 2000; Journal ID: ISSN 1098-0121
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; MANGANESE BASE ALLOYS; NICKEL ALLOYS; PHASE TRANSFORMATIONS; MAGNETIC SUSCEPTIBILITY; CRYSTAL STRUCTURE; NEUTRON DIFFRACTION; TEMPERATURE RANGE 0065-0273 K; MAGNETIC MOMENTS; ELECTRIC CONDUCTIVITY; FCC LATTICES; SPIN WAVES; EXPERIMENTAL DATA; THEORETICAL DATA

Citation Formats

Fishman, R. S., Lee, W.-T., Liu, S. H., Mandrus, D., Robertson, J. L., Song, K. J., University of Tennessee, Knoxville, Tennessee 37996-1200, and Thompson, J. R. Structural and magnetic phase transitions in Mn-Ni alloys. United States: N. p., 2000. Web. doi:10.1103/PhysRevB.61.12159.
Fishman, R. S., Lee, W.-T., Liu, S. H., Mandrus, D., Robertson, J. L., Song, K. J., University of Tennessee, Knoxville, Tennessee 37996-1200, & Thompson, J. R. Structural and magnetic phase transitions in Mn-Ni alloys. United States. doi:10.1103/PhysRevB.61.12159.
Fishman, R. S., Lee, W.-T., Liu, S. H., Mandrus, D., Robertson, J. L., Song, K. J., University of Tennessee, Knoxville, Tennessee 37996-1200, and Thompson, J. R. Mon . "Structural and magnetic phase transitions in Mn-Ni alloys". United States. doi:10.1103/PhysRevB.61.12159.
@article{osti_20216415,
title = {Structural and magnetic phase transitions in Mn-Ni alloys},
author = {Fishman, R. S. and Lee, W.-T. and Liu, S. H. and Mandrus, D. and Robertson, J. L. and Song, K. J. and University of Tennessee, Knoxville, Tennessee 37996-1200 and Thompson, J. R.},
abstractNote = {When the Ni concentration exceeds about 18%, Mn-Ni alloys were expected to support two different noncollinear spin-density wave (SDW) phases. A triple-Q SDW with moments along the crystal diagonals was believed to appear in the fcc phase between T{sub N} and T{sub t}. Below T{sub t}, the fct phase with c>a was believed to contain a double-Q SDW with moments in the ab plane and at 45 degree sign angles from the crystal axes. Based on resistivity, neutron-scattering, and susceptibility measurements, we show that the structural and magnetic phase transitions in a Mn{sub 1-x}Ni{sub x} alloy with x{approx_equal}0.20 are actually distinct, with the structural phase transition at T{sub t}{approx_equal}250 K lying far above the magnetic transition at T{sub m}{approx_equal}125 K. A Hamiltonian which includes elastic, magnetoelastic, and noncollinearity energies is used to describe these two transitions. In the tetragonal phase between T{sub t} and T{sub m}, our model predicts a new SDW phase with moments tilted away from the crystal diagonals toward the ab plane. The energy gap in the spin-wave spectrum is predicted to change discontinuously at T{sub m}. (c) 2000 The American Physical Society.},
doi = {10.1103/PhysRevB.61.12159},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
issn = {1098-0121},
number = 18,
volume = 61,
place = {United States},
year = {2000},
month = {5}
}