Magnetic Anisotropy of Ferromagnetic Martensites

2011 ◽  
Vol 684 ◽  
pp. 31-47 ◽  
Author(s):  
Victor A. L'vov ◽  
Volodymyr A. Chernenko
Keyword(s):  
Phase Transitions ◽  
Energy Density ◽  
Magnetic Anisotropy ◽  
Magnetocrystalline Anisotropy ◽  
Landau Theory ◽  
Theoretical Studies ◽  
Ferromagnetic Shape Memory Alloys ◽  
Ferromagnetic Shape Memory ◽  
Experimental And Theoretical Studies ◽  
Magnetocrystalline Anisotropy Energy

The analytic survey of experimental and theoretical studies of the magnetic anisotropy of ferromagnetic shape memory alloys (FSMAs) is presented. The interdependence between the magnetic anisotropy of FSMAs, their lattice parameters, microstructure, and magnetostrain properties is considered. The temperature dependencies of the magnetocrystalline anisotropy energy density (MAED) and magnetically induced mechanical stress are described in the framework of magnetoelastic model based on Landau theory of phase transitions. The magnetic anisotropy of thin martensitic platelets/films and wires is considered. The effect of compensation of magnetocrystalline anisotropy by the magnetostatic one is studied. The reduction of MAED as a result of internal twinning of single crystal is discussed. The possibility of observation of reversible magnetic-fieldinduced strain in the twinned FSMAs with reduced MAED is demonstrated.

Experimental and Theoretical Studies on the Magnetic Anisotropy in Lanthanide(III)-Centered Fe3Ln Propellers

2015 ◽  
Vol 21 (34) ◽  
pp. 12171-12180 ◽  
Author(s):  
Luca Rigamonti ◽  
Andrea Nava ◽  
Marie-Emmanuelle Boulon ◽  
Javier Luzon ◽  
Roberta Sessoli ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Theoretical Studies ◽  
Experimental And Theoretical Studies

Phase Diagrams for Incommensurate Systems

1982 ◽  
Vol 21 ◽  
Author(s):  
P. Toledano
Keyword(s):  
Free Energy ◽  
Phase Transitions ◽  
Energy Density ◽  
Phase Diagrams ◽  
Order Parameter ◽  
Landau Theory ◽  
Free Energy Density ◽  
Lock In

ABSTRACTPhase diagrams, for systems undergoing one or several incommensurate and lock-in transitions, are discussed in the framework of the Landau theory of phase transitions. It is shown that their essential features can be deduced from the explicit forms of the free-energy density ø and the k-dispersion of the coefficient α(→k)of the quadratic contribution of the order-parameter components in ø. Two families of phase diagrams are distinguished depending on symmetry considerations.

scholarly journals Temperature Dependence of Anisotropy in Ti and Gd Doped NiMnGa-Based Multifunctional Ferromagnetic Shape Memory Alloys

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2906
Author(s):  
Amadeusz Łaszcz ◽  
Mariusz Hasiak ◽  
Jerzy Kaleta
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Temperature Dependence ◽  
Magnetocrystalline Anisotropy ◽  
Anisotropy Constant ◽  
Anisotropy Energy ◽  
Ferromagnetic Shape Memory Alloys ◽  
Effective Anisotropy ◽  
Effective Anisotropy Constant ◽  
Ferromagnetic Shape Memory

The temperature dependence of magnetocrystalline anisotropy was investigated in detail for the polycrystalline Ni50Mn25Ga25, Ni50Mn25Ga20Ti5 and Ni50Mn25Ga20Gd5 ferromagnetic shape memory alloys in the temperature range of 50–400 K. The effective anisotropy constant was estimated from a series of high field magnetization curves based on the fitting procedure according to the law of approach to magnetic saturation. The low temperature martensitic phase was found to have a significantly higher anisotropy energy in comparison to a high temperature austenitic phase, which was observed through a sudden, distinct drop of anisotropy energy. The calculated values of the effective anisotropy constant were comparable to the results published by other authors. Moreover, the strong influence of chemical composition on the first-order phase transition and the second-order ferromagnetic to the paramagnetic transition was revealed. Finally, the strong coupling between the temperature dependence of the coercive field and the temperature dependence of magnetocrystalline anisotropy was also shown and discussed in the present study.

scholarly journals Evaluation of the Magnetocrystalline Anisotropy of Typical Materials Using MBN Technology

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3330
Author(s):  
Liting Wang ◽  
Cunfu He ◽  
Xiucheng Liu
Keyword(s):  
Magnetic Anisotropy ◽  
Magnetocrystalline Anisotropy ◽  
Electron Backscatter Diffraction ◽  
Pipeline Steel ◽  
Experimental System ◽  
Experimental Results ◽  
Anisotropy Energy ◽  
Ebsd Technique ◽  
Backscatter Diffraction ◽  
Magnetocrystalline Anisotropy Energy

Magnetic Barkhausen noise (MBN) signals in the stage from saturation to remanence of the hysteresis loop are closely correlated with magnetocrystalline anisotropy energy. MBN events in this stage are related to the nucleation and growth of reverse domains, and mainly affected by the crystallographic textures of materials. This paper aims to explore the angle-dependent magnetocrystalline anisotropy energy. Based on the consideration of macroscopic magnetic anisotropy, with the concept of coordinate transformation, a model was firstly established to simulate the magnetocrystalline anisotropy energy (MCE) of a given material. Secondly, the MBN signals in different directions were tested with a constructed experimental system and the characteristic parameters extracted from the corresponding stage were used to evaluate the magnetic anisotropy of the material. Finally, the microstructures of 4 materials were observed with a metallographic microscope. The microtextures of local areas were measured with the electron backscatter diffraction (EBSD) technique. The MBN experimental results obtained under different detection parameters showed significant differences. The optimal MBN detection parameters suitable for magnetic anisotropy research were determined and the experimental results were consistent with the results of MCE model. The study indicated that MBN technology was applicable to evaluate the MCE of pipeline steel and oriented silicon steel, especially pipeline steel.

Size-dependent phase transitions and phase reversal at the nanoscale

2017 ◽  
Author(s):  
Amanda S. Barnard
Keyword(s):  
Phase Transitions ◽  
Size Range ◽  
Solution Chemistry ◽  
Physical Parameters ◽  
Theoretical Studies ◽  
Phase Reversal ◽  
Size Dependent ◽  
The Stability ◽  
Experimental And Theoretical Studies ◽  
Phase Relationships

This article investigates size-dependent phase transitions and phase reversal at the nanoscale. In general, the crystallization of a nanomaterial into a particular structure is kinetically driven. However, the choice of which structure occurs in a specific size range is often a result of thermodynamics. These size-dependent phase relationships may be explored by analyzing the free energy and enthalpy of formation. This article considers the size-dependent phase stability of nanomaterials based on experimental and theoretical studies of zirconia and titania. It describes the use of bulk phase diagrams to capture important information on the stability of materials. It also highlights some of the physical parameters that influence phase transitions and phase reversal at the nanoscale, including temperature, pressure, shape, solution chemistry, surface chemistry and surface charge.

scholarly journals Rationalizing the sign and magnitude of the magnetic coupling and anisotropy in dinuclear manganese(iii) complexes

2018 ◽  
Vol 47 (34) ◽  
pp. 11820-11833 ◽  
Author(s):  
Kuduva R. Vignesh ◽  
Stuart K. Langley ◽  
Christopher J. Gartshore ◽  
Ivana Borilović ◽  
Craig M. Forsyth ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Magnetic Coupling ◽  
Theoretical Studies ◽  
Exchange Contribution ◽  
Experimental And Theoretical Studies

Combined experimental and theoretical studies on a family of twelve MnIII dimers reveal that exchange contribution to the magnetic anisotropy is as important as single ion anisotropy.

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