Effect of Acoustic Oscillations on Non-Equilibrium State of Magnetic Domain Structure in Cubic Ni<sub>2</sub>MnGa Single Crystal
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 magne...
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| author | Anxo Fernández González Konstantin Sapozhnikov Pavel Pal-Val Sergey Kustov |
| author_facet | Anxo Fernández González Konstantin Sapozhnikov Pavel Pal-Val Sergey Kustov |
| author_sort | Anxo Fernández González |
| collection | DOAJ |
| description | 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 Ni<sub>2</sub>MnGa 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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| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-11T05:32:56Z |
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| spelling | doaj.art-89e1a16bba0b49d88bffdbfab40da9832023-11-17T17:01:33ZengMDPI AGMaterials1996-19442023-03-01167254710.3390/ma16072547Effect of Acoustic Oscillations on Non-Equilibrium State of Magnetic Domain Structure in Cubic Ni<sub>2</sub>MnGa Single CrystalAnxo Fernández González0Konstantin Sapozhnikov1Pavel Pal-Val2Sergey Kustov3Departament de Física, Universitat de les Illes Balears, Cra Valldemossa km 7.5, 07122 Palma de Mallorca, SpainSolid State Physics Division, Ioffe Institute, Politekhnicheskaya 26, 194021 St. Petersburg, RussiaB. Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, Nauky Ave. 47, 61101 Kharkiv, UkraineDepartament de Física, Universitat de les Illes Balears, Cra Valldemossa km 7.5, 07122 Palma de Mallorca, SpainMagnetic 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 Ni<sub>2</sub>MnGa 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.https://www.mdpi.com/1996-1944/16/7/2547magnetic shape memory alloysultrasonicsinternal frictionreversible Villari effectmagnetic domain walls |
| spellingShingle | Anxo Fernández González Konstantin Sapozhnikov Pavel Pal-Val Sergey Kustov Effect of Acoustic Oscillations on Non-Equilibrium State of Magnetic Domain Structure in Cubic Ni<sub>2</sub>MnGa Single Crystal Materials magnetic shape memory alloys ultrasonics internal friction reversible Villari effect magnetic domain walls |
| title | Effect of Acoustic Oscillations on Non-Equilibrium State of Magnetic Domain Structure in Cubic Ni<sub>2</sub>MnGa Single Crystal |
| title_full | Effect of Acoustic Oscillations on Non-Equilibrium State of Magnetic Domain Structure in Cubic Ni<sub>2</sub>MnGa Single Crystal |
| title_fullStr | Effect of Acoustic Oscillations on Non-Equilibrium State of Magnetic Domain Structure in Cubic Ni<sub>2</sub>MnGa Single Crystal |
| title_full_unstemmed | Effect of Acoustic Oscillations on Non-Equilibrium State of Magnetic Domain Structure in Cubic Ni<sub>2</sub>MnGa Single Crystal |
| title_short | Effect of Acoustic Oscillations on Non-Equilibrium State of Magnetic Domain Structure in Cubic Ni<sub>2</sub>MnGa Single Crystal |
| title_sort | effect of acoustic oscillations on non equilibrium state of magnetic domain structure in cubic ni sub 2 sub mnga single crystal |
| topic | magnetic shape memory alloys ultrasonics internal friction reversible Villari effect magnetic domain walls |
| url | https://www.mdpi.com/1996-1944/16/7/2547 |
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