scholarly journals Compositional Dependence of Magnetocrystalline Anisotropy in Fe-, Co-, and Cu-Alloyed Ni-Mn-Ga

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 133
Author(s):  
Michal Rameš ◽  
Vít Kopecký ◽  
Oleg Heczko
Keyword(s):  
Magnetic Anisotropy ◽  
Magnetocrystalline Anisotropy ◽  
Compositional Dependence ◽  
Transformation Temperatures ◽  
Transitional Metals ◽  
Polycrystalline Alloys ◽  
Ferromagnetic Ordering

The key for the existence of magnetic induced reorientation is strong magnetocrystalline anisotropy, i.e., the coupling between ferroelastic and ferromagnetic ordering. To increase the transformation temperatures and thus functionality, various elemental alloying in Ni-Mn-Ga is tried. We analyzed more than twenty polycrystalline alloys alloyed by small amount (up to 5atom%) of transitional metals Co, Fe, Ni, and Cu for the value of magnetic anisotropy in search of general trends with alloying. In agreement with previous reports, we found that maximum anisotropy occurs at stoichiometric Ni2MnGa and any alloying decreases its value. The strongest decrease of the anisotropy is observed in the case where the alloyed elements substitute Ga.

Effects of the Co-Presence of Conflicting Magnetic Anisotropy in Ba Ferrite Particles

2010 ◽  
Vol 67 ◽  
pp. 108-112
Author(s):  
Giancarlo Bottoni
Keyword(s):  
Thermal Stability ◽  
Magnetic Properties ◽  
Magnetic Anisotropy ◽  
Low Temperatures ◽  
Magnetocrystalline Anisotropy ◽  
Shape Anisotropy ◽  
Recording Media ◽  
Magnetization Switching ◽  
Crystalline Anisotropy ◽  
Thermal Stability Of

In Ba ferrite particles magnetocrystalline and shape anisotropies are contemporarily present and conflicting. The strength and evolution of the two anisotropies are studied, through the dependence of the anisotropy constants on temperature. While in pure Ba ferrite particles the anisotropy is uniaxial at all temperatures, since the magnetocrystalline anisotropy clearly prevails on shape anisotropy, in particles modified for employment in recording media the two anisotropies are comparable and at low temperatures the shape anisotropy result stronger than the crystalline anisotropy. Besides the irregular shape of the particles introduces further preferred directions for the magnetization. The Co/Ti-doped particles show a multiple axes anisotropy. The macroscopic magnetic properties are found in relationship with the evolution of the anisotropy. Also the influence that the presence of such multiple anisotropy has on the magnetization switching and on the thermal stability of the magnetization of the Ba ferrite particles is analyzed.

Soft Magnetic Properties and Microstructures for the Fe Based Sputtered Films with High Bs

1991 ◽  
Vol 232 ◽  
Author(s):  
Migaku Takahashi ◽  
T. Shimatsu
Keyword(s):  
Magnetic Anisotropy ◽  
Magnetocrystalline Anisotropy ◽  
Film Plane ◽  
Initial Permeability ◽  
Physical Origin ◽  
Soft Magnetic ◽  
Magnetic Anisotropy Energy ◽  
Local Anisotropy ◽  
Sputtered Films ◽  
Sufficient Reduction

ABSTRACTPhysical origin of high initial permeability, μi, in Fe based films with large magnetocrystalline anisotropy and magnetostriction is systematically discussed in connection with the microstructure of the films. In order to decrease the local anisotropy fluctuation to determine μi in these films, decrease of effective magnetic anisotropy, Ueff, of each grain mainly caused by the sufficient reduction of grain size is required. Induced uniaxial magnetic anisotropy energy, Ku, in film plane plays an important role to decrease Ueff through the micromagnetic interaction. The ratio of Ueff /Ku proposed as the important key to analyse the magnetization process. The dependence of μi Ku is classified concerning for Ueff/Ku.

Easy-plane magnetic anisotropy in layered GdMn2Si2 compound with easy-axis magnetocrystalline anisotropy

2020 ◽  
Vol 818 ◽  
pp. 152902
Author(s):  
E.G. Gerasimov ◽  
P.B. Terentev ◽  
A.F. Gubkin ◽  
H.E. Fischer ◽  
D.I. Gorbunov ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Easy Axis ◽  
Magnetocrystalline Anisotropy ◽  
Easy Plane

scholarly journals Perpendicular Magnetic Anisotropy and Intralayer Interactions in a Single Layer of CoPt Nanoparticles

2016 ◽  
Vol 257 ◽  
pp. 60-63
Author(s):  
Javier Rubín ◽  
Adriana I. Figueroa ◽  
Jolanta Stankiewicz ◽  
Fernando Bartolomé ◽  
Luis Miguel García ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Particle Diameter ◽  
Single Layer ◽  
Perpendicular Magnetic Anisotropy ◽  
Interlayer Coupling ◽  
Freezing Temperature ◽  
Squid Magnetometry ◽  
Granular Film ◽  
Sequential Deposition ◽  
Ferromagnetic Ordering

The multilayer films [Al2O3/tCo Co/tPt Pt]N, produced by sequential deposition of Co and Pt on alumina consist in layers of CoPt alloyed nanoparticles. They show perpendicular magnetic anisotropy (PMA) below a freezing temperature Tf, an asperomagnetic-like phase below that temperature, and hard ferromagnetic ordering below a transition temperature T1 < Tf. A single layer granular film (N = 1) with deposition thicknesses tCo=0.7 nm, tPt=1.5 nm and particle diameter of 3 nm is presently studied. SQUID magnetometry shows that a single layer presents the three phases as well. Para-, aspero-and ferromagnetic phases are observed upon lowering the temperature, with transition temperatures Tf ≈ 375 K and T1 ≈ 200 K, respectively. In addition, the PMA persists, proving that there is no interlayer coupling in the multilayer system. SQUID results also reveal a core-shell structure in the CoPt nanoparticles.

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.

Magnetization reversal and magnetic anisotropy of Fe, Ni and Co nanowires in nanoporous alumina membranes

2001 ◽  
Vol 674 ◽  
Author(s):  
M. Kröll ◽  
L. J. de Jongh ◽  
F. Luis ◽  
P. Paulus ◽  
G. Schmid
Keyword(s):  
Magnetic Anisotropy ◽  
Magnetization Reversal ◽  
Low Temperatures ◽  
Magnetocrystalline Anisotropy ◽  
Small Diameter ◽  
Anisotropy Constant ◽  
Magnetic Domains ◽  
Alumina Membranes ◽  
Subsequent Propagation ◽  
Co Nanowires

ABSTRACTThe magnetization reversal and magnetic anisotropy of Fe, Ni and Co nanowires is studied at low temperatures. All nanowires show a strong shape anisotropy with the easy axis being parallel to the long axis of the wires. Co nanowires additionally show a temperature dependent magnetocrystalline anisotropy along the hexagonal c-axis, which is directed nearly perpendicular to the long axis of the wires, as is confirmed by X-Ray diffraction measurements [1] and reported by Strijkers et al. who performed NMR measurements on samples prepared in a similar way [2]. Therefore, at low temperatures and for large wire diameters a competition between magnetocrystalline and shape anisotropies can be observed. Co wires with a small diameter, however, do not show a significant magnetocrystalline anisotropy. Fcc-Co, which is only known as a high-temperature Co modification and which does not have a large magnetocrystalline anisotropy constant, becomes the predominant Co modification here [1,3]. Investigations on the size dependence of the switching field for Fe and Ni nanowires provide information about the magnetization reversal process, which takes place via a nucleation of small magnetic domains probably at the end of the wires, and subsequent propagation of the domain wall along the wire.

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