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Title: Strain-induced dimensionality crossover of precursor modulations in Ni{sub 2}MnGa

Precursor modulations often occur in functional materials like magnetic shape memory alloys, ferroelectrics, and superconductors. In this letter, we have revealed the underlying mechanism of the precursor modulations in ferromagnetic shape memory alloys Ni{sub 2}MnGa by combining synchrotron-based x-ray diffraction experiments and first-principles phonon calculations. We discovered the precursor modulations along [011] direction can be eliminated with [001] uniaxial loading, while the precursor modulations or premartensite can be totally suppressed by hydrostatic pressure condition. The TA{sub 2} phonon anomaly is sensitive to stress induced lattice strain, and the entire TA{sub 2} branch is stabilized along the directions where precursor modulations are eliminated by external stress. Our discovery bridges precursor modulations and phonon anomalies, and sheds light on the microscopic mechanism of the two-step superelasticity in precursor martensite.
Authors:
 [1] ;  [2] ; ; ;  [3] ;  [4] ;  [5] ;  [6] ;  [4] ;  [7]
  1. School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China)
  2. State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)
  3. Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)
  4. High Pressure Synergetic Consortium (HPSynC), Geophysical Laboratory, Carnegie Institution of Washington, Argonne, Illinois 60439 (United States)
  5. X-Ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
  6. State Key Laboratory for Fabrication and Processing of Nonferrous Metals, General Research Institute for Nonferrous Metals, Beijing 100088 (China)
  7. (HPSTAR), Pudong, Shanghai 201203 (China)
Publication Date:
OSTI Identifier:
22399101
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 2; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CRYSTAL STRUCTURE; FERROELECTRIC MATERIALS; GALLIUM ALLOYS; LOADING; MANGANESE ALLOYS; MARTENSITE; MODULATION; NICKEL ALLOYS; PHONONS; PRECURSOR; SHAPE MEMORY EFFECT; STRAINS; STRESSES; SUPERCONDUCTORS; SYNCHROTRON RADIATION; VISIBLE RADIATION; X-RAY DIFFRACTION