Temperature Dependence of Magneto-Mechanical Response in Ni-Mn-Ga Magnetic Shape Memory Alloys

2004 ◽  
Vol 855 ◽  
Author(s):  
Leon M. Cheng ◽  
Garrett Landry ◽  
hannon P. Farrell ◽  
Rosaura Ham-Su ◽  
Calvin V. Hyatt
Keyword(s):  
Magnetic Field ◽  
Mechanical Response ◽  
Anisotropy Constant ◽  
Systematic Investigation ◽  
Critical Magnetic Field ◽  
Effect Of Temperature ◽  
Magnetic Shape Memory ◽  
Magnetic Anisotropy Constant ◽  
Maximum Magnetic Field ◽  
Magnetic Forces

ABSTRACTIn this work, a systematic investigation is being carried out on single crystals of Ni47.8Mn27.5Ga24.7 alloy to determine the effect of temperature on the magneto-mechanical behaviour of the Ni-Mn-Ga alloys. Repeated mechanical and magnetic forces have been applied at various temperatures below the martensite finish (MF) temperature. It has been observed that twinning start and finish stresses, critical magnetic field and maximum magnetic-field-induced strain all remain almost constant within about 20K below MF and then change substantially at lower temperatures. Eventually no magnetic-field-induced strain can be observed at temperatures below 262K. It is proposed that although magnetic anisotropy constant increases with decreasing temperature, it is not sufficient to overcome the increasing twinning stresses required for twin boundary motion at lower temperatures.

scholarly journals Влияние дисперсии магнитной анизотропии кластеров Ge-=SUB=-3-=/SUB=-Mn-=SUB=-5-=/SUB=- на температурные зависимости намагниченности тонких пленок Ge:Mn

2019 ◽  
Vol 45 (2) ◽  
pp. 36
Author(s):  
А.И. Дмитриев ◽  
М.С. Дмитриева ◽  
Г.Г. Зиборов
Keyword(s):  
Magnetic Field ◽  
Magnetic Anisotropy ◽  
Lognormal Distribution ◽  
Anisotropy Constant ◽  
Zero Field ◽  
Magnetization Curves ◽  
Magnetic Anisotropy Energy ◽  
Size Dependent ◽  
Magnetic Anisotropy Constant ◽  
Temperature Dependences

AbstractThe temperature dependences of magnetization M ( T ) of thin ion-implanted Ge:Mn (4 at % Mn) films containing Ge_3Mn_5 clusters were measured on samples cooled in the absence of magnetic field (zero field cooled, ZFC) and in a magnetic field of 10 kOe (field-cooled, FC). It has been established that the shape of ZFC–FC differential M ( T ) curves is determined by lognormal distribution of the size-dependent magnetic anisotropy energy of Ge_3Mn_5 clusters. Analysis of the observed ZFC–FC magnetization curves allowed the magnetic anisotropy dispersion (variance) and magnetic anisotropy constant to be estimated.

Experiments and Modeling of the Magneto-Mechanical Response of Magnetic Shape Memory Alloys

2009 ◽  
Author(s):  
Heidi P. Feigenbaum ◽  
Constantin Ciocanel
Keyword(s):  
Magnetic Field ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Constant Magnetic Field ◽  
Mechanical Response ◽  
Magnetic Flux Density ◽  
Magnetic Shape Memory ◽  
Magnetic Shape Memory Alloys ◽  
Power Harvesting ◽  
Axial Compressive Stress

Magnetic shape memory alloys (MSMAs) are relatively new materials that exhibit a magnetic shape memory effect as a result of the rearrangement of martensitic variants under the influence of magnetic fields. Due to the MSMAs newness there is limited understanding of their magneto-mechanical behavior. This work presents experimental and modeling results of MSMAs for cases in which the material is loaded and unloaded in uniaxial compression in the presence of a constant magnetic field. The experiments are performed with the magnetic field applied perpendicular and at an angle to the mechanical loading axis. During the loading and unloading process, the evolution of the magnetic flux density is monitored to assess the potential of these materials for power harvesting applications. The modeling is based on the thermodynamic approach proposed by Kiefer and Lagoudas [1]. This model was modified and calibrated to reproduce material response under biaxial constant magnetic field and variable uni-axial compressive stress. Comparing the experimental and simulated results, one can recognize that further work is needed to improve the model.

Magnetic Anisotropy in [Pt/Co]4/MgO/[Co/Pt]2 Multilayers

2019 ◽  
Vol 944 ◽  
pp. 625-630
Author(s):  
Qian Li ◽  
Lei Li ◽  
Wei Zhou ◽  
Jun Chen ◽  
Si Yuan Zhang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Anisotropy ◽  
Perpendicular Magnetic Anisotropy ◽  
Interlayer Coupling ◽  
Periodic Variation ◽  
Anisotropy Constant ◽  
Soft Layer ◽  
Magnetic Anisotropy Constant ◽  
Extraordinary Hall Effect ◽  
The Magnetic Field

A serial of [Pt/Co]4/MgO/[Co/Pt]2multilayers were prepared by magnetron sputtering in this study and Antiferromagnetic (AF) interlayer coupling was observed with increasing MgO spacer thickness. Perpendicular magnetic anisotropy of soft layer in [Pt/Co]4/MgO/[Co/Pt]2multilayers were measured by Extraordinary Hall Effect (EHE). The direction of the magnetic field was parallel to the direction of the current. The results revealed that perpendicular magnetic anisotropy constant Kuoscillates with the thickness of MgO layer which is between 1.3 to 3.3 nm. The period of this oscillation is about 0.43 nm. This is very close to the monolayer (100) MgO. With increasing MgO spacer, the periodic variation of interface between [Pt/Co]nand MgO layer may be one of the reasons for this oscillation behavior of Ku.

scholarly journals Магнитные и упругие колебания в кристаллах марганец-цинковой шпинели в зависимости от константы анизотропии

2018 ◽  
Vol 60 (6) ◽  
pp. 1142
Author(s):  
Л.Н. Котов ◽  
П.А. Северин ◽  
В.С. Власов ◽  
Д.С. Безносиков ◽  
Е.Л. Котова ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Elastic Constants ◽  
Constant Magnetic Field ◽  
Magnetization Vector ◽  
Anisotropy Constant ◽  
Coupling Constants ◽  
Saturation Field ◽  
Magnetic Anisotropy Constant ◽  
Elastic Dynamics ◽  
Elastic Shear

AbstractThe amplitudes of magnetic and elastic vibrations for Mn_0.61Zn_0.35Fe_2.04O_4 spinel crystalline slab are calculated by solving the equations describing the magnetic and elastic dynamics. The anisotropy constants, magnetization, second-order elastic constants and magnetoelastic coupling constants for a studied crystal are expressed as the functions of temperature. The magnetization vector and elastic shear components are found as the functions of the first magnetic anisotropy constant at different values of an external constant magnetic field greater than a saturation field. The procession patterns for normally and tangentially magnetized slabs are displayed for two values of the first anisotropy constant. High absolute values of the first anisotropy constant are shown to refer to reorientation of the magnetization vector.

Enhanced critical magnetic field for monoatomic-layer superconductor by Josephson junction steps

2021 ◽  
Vol 103 (8) ◽  
Author(s):  
Fumikazu Oguro ◽  
Yudai Sato ◽  
Kanta Asakawa ◽  
Masahiro Haze ◽  
Yukio Hasegawa
Keyword(s):  
Magnetic Field ◽  
Josephson Junction ◽  
Critical Magnetic Field

Magnetocrystalline Anisotropy and Twinning Stress of 10M and 2M Martensites in Ni-Mn-Ga System

2006 ◽  
Vol 512 ◽  
pp. 195-200 ◽  
Author(s):  
Nariaki Okamoto ◽  
Takashi Fukuda ◽  
Tomoyuki Kakeshita ◽  
Tetsuya Takeuchi
Keyword(s):  
Magnetic Field ◽  
Shear Stress ◽  
Magnetocrystalline Anisotropy ◽  
Anisotropy Constant ◽  
The Other ◽  
Magnetic Shear ◽  
Maximum Value ◽  
Twinning Plane ◽  
Twinning Shear ◽  
The Difference

Ni2MnGa alloy with 10M martensite exhibits rearrangement of martensite variants (RMV) by magnetic field, but Ni2.14Mn0.92Ga0.94 with 2M martensite does not. In order to explain the difference, we measured uniaxial magnetocrystalline anisotropy constant Ku and the stress required for twinning plane movement τreq in these alloys. Concerning the former alloy, the maximum value of magnetic shear stress acting across twinning plane τmag, which is evaluated as |Ku| divided by twinning shear, becomes larger than τr eq. On the other hand, concerning the latter alloy, the maximum of τmag is only one-tenth of τreq at any temperature examined. Obviously, the relation, τmag> τr eq, is satisfied when RMV occurs by magnetic field and vice versa. In this martensite, the large twinning shear of 2M martensite is responsible for small τmag and large τreq.

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