Elastic and Anelastic Magnetomechanical Phenomena Close to the Premartensitic Transition in Ni-Mn-Ga

Abstract

[eng] The temperature and field dependences of internal friction (IF) and Young’s modulus (YM) are studied using longitudinal resonant oscillations (90 kHz) technique in stoichiometric ferromagnetic Ni2MnGa single crystal along the [100] direction, close to the premartensitic transformation temperature, TPM, in the demagnetized state and under moderate fields. It is shown that: the apparent Young’s modulus softens close to TPM under moderate fields, instead of the hardening outside this range. This effect and other previously reported as the splitting IF peak and YM minimum damping during premartensitic transition are interpreted in terms of superposition of classical magnetic domain wall -related Microeddy and Macroeddy current relaxations, which have not been considered so far as the origin of premartensitic anelastic effects in Ni2MnGa.