Large Non-ergodic Magnetoelastic Damping in Ni–Mn–Ga Austenite

Bodnárová, Lucie; Sedlák, Petr; Heczko, Oleg; Seiner, Hanuš

doi:10.1007/s40830-020-00272-4

Cited by 5 publications

(1 citation statement)

References 30 publications

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“…The authors of Refs. [ 22 , 23 ] have revealed a significant role of magnetic domain structure in magnetoelastic effects of the cubic nearly stoichiometric Ni 2 MnGa, but no attempt has been made to analyze the magnetoelastic effects in terms of canonical components of the magnetomechanical IF impeding consistent interpretation of the field, frequency, and strain amplitude dependences of the anelastic effects in cubic ferromagnetic Ni 2 MnGa. This gap is essentially filled in Refs.…”

Section: Introductionmentioning

confidence: 99%

Effect of Acoustic Oscillations on Non-Equilibrium State of Magnetic Domain Structure in Cubic Ni2MnGa Single Crystal

et al. 2023

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Magnetic hysteresis is a manifestation of non-equilibrium state of magnetic domain walls trapped in local energy minima. Using two types of experiments we show that, after application of a magnetic field to a ferromagnet, acoustic oscillations excited in the latter can “equilibrate” metastable magnetic domain structure by triggering the motion of domain walls into more stable configurations. Single crystals of archetypal Ni2MnGa magnetic shape memory alloy in the cubic phase were used in the experiments. The magnetomechanical absorption of ultrasound versus strain amplitude was studied after step-like changes of a polarizing magnetic field. One-time hysteresis was observed in strain amplitude dependences of magnetomechanical internal friction after step-like variations of a polarizing field. We distinguish two ingredients of the strain amplitude hysteresis that are found in the ranges of linear and non-linear internal friction and show qualitatively different behavior for increasing and decreasing applied polarizing fields. The uncovered effect is interpreted in terms of three canonical magnetomechanical internal friction terms (microeddy, macroeddy and hysteretic) and attributed to “triggering” by acoustic oscillations of the irreversible motion of domain walls trapped in the metastable states. To confirm the suggested interpretation we determine the coercive field of magnetization hysteresis through the measurements of the reversible Villari effect. We show that the width of the hysteresis loops decreases when acoustic oscillations in the non-linear range of domain wall motion are excited in the crystal. The observed “equilibration” of the magnetic domain structure by acoustic oscillations is attributed to the periodic stress anisotropy field induced by oscillatory mechanical stress.

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Section: Introductionmentioning

confidence: 99%