Lattice dynamics in magnetic superelastic Ni-Mn-In alloys: Neutron scattering and ultrasonic experiments

TitleLattice dynamics in magnetic superelastic Ni-Mn-In alloys: Neutron scattering and ultrasonic experiments
Publication TypeJournal Article
Year of Publication2009
AuthorsMoya X, Gonzalez-Alonso D, Manosa L, Planes A, Garlea VO, Lograsso TA, Schlagel DL, Zarestky JL, Aksoy S, Acet M
Journal TitlePhysical Review B
Volume79
Pages214118
Date Published06/01
ISBN Number1098-0121
Accession NumberISI:000267699200048
Keywordsbehavior, elastic-constants, ni2mnga, premartensitic phenomena, shape-memory alloys, transition
Abstract

Neutron scattering and ultrasonic methods have been used to study the lattice dynamics of two single crystals of Ni-Mn-In Heusler alloys close to Ni50Mn34In16 magnetic superelastic composition. The paper reports on the experimental determination of the low-lying phonon-dispersion curves and the elastic constants for this alloy system. We found that the frequencies of the TA(2) branch are relatively low and it exhibits a small dip anomaly at a wave number xi(0) approximate to 1/3, which softens with decreasing temperature. Associated with the softening of this phonon, we also observed the softening of the shear elastic constant C' = (C-11-C-12)/2. Both temperature softenings are typical for bcc-based solids which undergo martensitic transformations and reflect the dynamical instability of the cubic lattice against shearing of {110} planes along < 1 (1) over bar0 > directions. Additionally, we measured low-lying phonon-dispersion branches and elastic constants in applied magnetic fields aimed to characterize the magnetoelastic coupling.

URL<Go to ISI>://000267699200048
DOI10.1103/Physrevb.79.214118