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Fernández González A, Sapozhnikov K, Pal-Val P, Kustov S. Effect of Acoustic Oscillations on Non-Equilibrium State of Magnetic Domain Structure in Cubic Ni 2MnGa Single Crystal. MATERIALS (BASEL, SWITZERLAND) 2023; 16:2547. [PMID: 37048841 PMCID: PMC10095562 DOI: 10.3390/ma16072547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 03/18/2023] [Accepted: 03/19/2023] [Indexed: 06/19/2023]
Abstract
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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Affiliation(s)
- Anxo Fernández González
- Departament de Física, Universitat de les Illes Balears, Cra Valldemossa km 7.5, 07122 Palma de Mallorca, Spain
| | - Konstantin Sapozhnikov
- Solid State Physics Division, Ioffe Institute, Politekhnicheskaya 26, 194021 St. Petersburg, Russia
| | - Pavel Pal-Val
- B. Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, Nauky Ave. 47, 61101 Kharkiv, Ukraine
| | - Sergey Kustov
- Departament de Física, Universitat de les Illes Balears, Cra Valldemossa km 7.5, 07122 Palma de Mallorca, Spain
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Martin N, Bannenberg LJ, Deutsch M, Pappas C, Chaboussant G, Cubitt R, Mirebeau I. Field-induced vortex-like textures as a probe of the critical line in reentrant spin glasses. Sci Rep 2021; 11:20753. [PMID: 34675354 PMCID: PMC8531314 DOI: 10.1038/s41598-021-99860-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 09/29/2021] [Indexed: 11/09/2022] Open
Abstract
We study the evolution of the low-temperature field-induced magnetic defects observed under an applied magnetic field in a series of frustrated amorphous ferromagnets (Fe\documentclass[12pt]{minimal}
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\begin{document}$$_{x}$$\end{document}x”). Combining small-angle neutron scattering and Monte Carlo simulations, we show that the morphology of these defects resemble that of quasi-bidimensional spin vortices. They are observed in the so-called “reentrant” spin-glass (RSG) phase, up to the critical concentration \documentclass[12pt]{minimal}
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\begin{document}$$x_{\mathrm{C}} \approx 0.36$$\end{document}xC≈0.36 which separates the RSG and “true” spin glass (SG) within the low temperature part of the magnetic phase diagram of a-Fe1−xMnx. These textures systematically decrease in size with increasing magnetic field or decreasing the average exchange interaction, and they finally disappear in the SG sample (\documentclass[12pt]{minimal}
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\begin{document}$$x = 0.41$$\end{document}x=0.41), being replaced by field-induced correlations over finite length scales. We argue that the study of these nanoscopic defects could be used to probe the critical line between the RSG and SG phases.
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Affiliation(s)
- N Martin
- Université Paris-Saclay, CNRS, CEA, Laboratoire Léon Brillouin, 91191, Gif-sur-Yvette, France.
| | - L J Bannenberg
- Faculty of Applied Science, Delft University of Technology, 2629 JB, Delft, The Netherlands
| | - M Deutsch
- CNRS, CRM2, Université de Lorraine, Nancy, France
| | - C Pappas
- Faculty of Applied Science, Delft University of Technology, 2629 JB, Delft, The Netherlands
| | - G Chaboussant
- Université Paris-Saclay, CNRS, CEA, Laboratoire Léon Brillouin, 91191, Gif-sur-Yvette, France
| | - R Cubitt
- Institut Laue Langevin, BP156, 38042, Grenoble, France
| | - I Mirebeau
- Université Paris-Saclay, CNRS, CEA, Laboratoire Léon Brillouin, 91191, Gif-sur-Yvette, France
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Magnetic Domain Walls and Macroscopic Magnetization-Related Elastic and Anelastic Effects during Premartensitic Transition in Ni₂MnGa. MATERIALS 2019; 12:ma12030376. [PMID: 30691045 PMCID: PMC6384950 DOI: 10.3390/ma12030376] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 01/14/2019] [Accepted: 01/22/2019] [Indexed: 11/17/2022]
Abstract
The temperature and field dependences of internal friction and Young´s modulus are studied using a high-resolution ultrasonic (90 kHz) technique in stoichiometric ferromagnetic Ni₂MnGa shape memory alloy close to the premartensitic transformation temperature, TPM, in the demagnetized state and under moderate fields. Several new effects observed like an apparent Young´s modulus softening close to TPM under moderate fields, instead of the hardening outside this range, as well as existing controversies in the apparent elastic and anelastic properties of Ni₂MnGa close to TPM are explained by microeddy and macroeddy current relaxations that to date have been disregarded.
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