Investigation of an effective anisotropy field involved in photoinduced precession of magnetization in (Ga,Mn)As

2009 ◽  
Vol 105 (7) ◽  
pp. 07C519 ◽  
Author(s):  
S. Kobayashi ◽  
Y. Hashimoto ◽  
H. Munekata
Keyword(s):  
Anisotropy Field ◽  
Effective Anisotropy

Effect of Thickness on Mechanically Tunable Magnetic Anisotropy of FeGa Thin Films Deposited on Flexible Substrates

2015 ◽  
Vol 815 ◽  
pp. 227-232 ◽  
Author(s):  
Ying Yu ◽  
Shu Hong Xie ◽  
Qing Feng Zhan
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Magnetic Anisotropy ◽  
Effective Strain ◽  
Anisotropy Field ◽  
Saturation Field ◽  
Effective Anisotropy ◽  
Magnetostriction Constant ◽  
The Difference ◽  
Different Strains

A practical way to manipulate the magnetic anisotropy of magnetostrictive FeGa thin films grown on flexible polyethylene terephthalate (PET) substrates is introduced in this study. The effect of film thickness on magnetic properties and magnetostriction constant of polycrystalline FeGa thin films was investigated. The anisotropy field Hk of flexible FeGa films, i.e., the saturation field determined by fitting the hysteresis curves measured along the hard axis, was enhanced with increasing the tensile strain applied along the easy axis of the thin films, but this enhancement via strain became unconspicuous with increasing the thickness of FeGa films. In order to study the magnetic sensitivity of thin films responding to the external stress, we applied different strains on these films and measure the corresponding anisotropy field. Moreover, the effective magnetostriction constant of FeGa films was calculated from the changes of both anisotropy field and external strain based on the Villari effect. A Neel’s phenomenological model was developed to illustrate that the effective anisotropy field of FeGa thin films was contributed from both the constant volume term and the inverse thickness dependent surface term. Therefore, the magnetic properties for the volume and surface of FeGa thin films were different, which has been verified in this work by using vibrating sample magnetometer (VSM) and magneto-optic Kerr effect (MOKE) system. The anisotropy field contributed by the surface of FeGa film and obtained by MOKE is smaller than that contributed by the film volume and measured by VSM. We ascribed the difference in Hk to the relaxation of the effective strain applied on the films with increasing the thickness of films.

Effective anisotropy field variation of magnetite nanoparticles with size reduction

2008 ◽  
Vol 64 (2) ◽  
pp. 211-218 ◽  
Author(s):  
J. M. Vargas ◽  
E. Lima ◽  
R. D. Zysler ◽  
J. G. S. Duque ◽  
E. De Biasi ◽  
...  
Keyword(s):  
Magnetite Nanoparticles ◽  
Anisotropy Field ◽  
Size Reduction ◽  
Field Variation ◽  
Effective Anisotropy

Microwave Properties of Polymer Composites Containing Combinations of Micro- and Nano-Sized Magnetic Fillers

2008 ◽  
Vol 8 (2) ◽  
pp. 650-654 ◽  
Author(s):  
Svetoslav Kolev ◽  
Tatyana Koutzarova ◽  
Andrey Yanev ◽  
Chavdar Ghelev ◽  
Ivan Nedkov
Keyword(s):  
Magnetic Material ◽  
Magnetocrystalline Anisotropy ◽  
Average Particle Size ◽  
Anisotropy Field ◽  
Anisotropy Constant ◽  
Strontium Hexaferrite ◽  
Filler Concentration ◽  
Average Particle ◽  
Effective Anisotropy ◽  
Magnetite Particles

We investigated the microwave absorbing properties of composite bulk samples with nanostructured and micron-sized fillers. As magnetic fillers we used magnetite powder (Fe3O4 with low magnetocrystalline anisotropy) and strontium hexaferrite (SrFe12O19 with high magnetocrystalline anisotropy). The dielectric matrix consisted of silicone rubber. The average particle size was 30 nm for the magnetite powder and 6 μm for the strontium hexaferrite powder. The micron-sized SrFe12O19 powder was prepared using a solid-state reaction. We investigated the influence of the filler concentration and the filler ratio (Fe3O4/SrFe12O19) in the polymer matrix on the microwave absorption in a large frequency range (1 ÷ 18 GHz). The results obtained showed that the highly anisotropic particles become centers of clusterification and the small magnetite particles form magnetic balls with different diameter depending on the concentration. The effect of adding micron-sized SrFe12O19 to the nanosized Fe3O4 filler in composites absorbing structures has to do with the ferromagnetic resonance (FMR) shifting to the higher frequencies due to the changes in the ferrite filler's properties induced by the presence of a magnetic material with high magnetocrystalline anisotropy. The two-component filler possesses new values of the saturation magnetization and of the anisotropy constant, differing from those of both SrFe12O19 and Fe3O4, which leads to a rise in the effective anisotropy field. The results demonstrate the possibility to vary the composite's absorption characteristics in a controlled manner by way of introducing a second magnetic material.

Effect of the effective anisotropy field of soft layer on magnetic properties of soft/hard stacked media

2008 ◽  
Vol 320 (22) ◽  
pp. 3083-3087 ◽  
Author(s):  
Y. Wang ◽  
F.S. Li ◽  
J. Ariake ◽  
N. Honda ◽  
S. Ishio ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Anisotropy Field ◽  
Soft Layer ◽  
Effective Anisotropy

scholarly journals Size Dependence of the Magnetoelastic Properties of Metallic Glasses for Actuation Applications

Sensors ◽  
2019 ◽  
Vol 19 (19) ◽  
pp. 4296 ◽  
Author(s):  
Ariane Sagasti ◽  
Jon Gutiérrez ◽  
Andoni Lasheras ◽  
José Manuel Barandiarán
Keyword(s):  
Size Dependence ◽  
Anisotropy Field ◽  
Width Ratio ◽  
Effective Anisotropy ◽  
A Value ◽  
Magnetoelastic Properties ◽  
Demagnetizing Factor ◽  
Δe Effect ◽  
Exhaustive Study ◽  
Strip Geometry

We present an exhaustive study of the magnetoelastic properties of 24 strips with different rectangular dimensions, cut from a long ribbon of Metglas® 2826MB3. The strips have a length-to-width ratio R = L/w ranging from 2 to over 20. Significant variations of the apparent saturation Young’s modulus and the ΔE effect with strip geometry, changing from 160 GPa and 4% for L = 10 mm, w = 5 mm and R = 2, to 164 GPa and 9.6% for L = 35 mm, w = 1.7 mm and R = 20.6, have been observed. In order to obtain the highest values of the ΔE effect, the magnetomechanical coupling coefficient, k, and the quality factor of the resonance, Q, a value R > 14 is needed. The effective anisotropy field Hk*, taken as the minimum of the E(H) curve, and its width ΔH, are not as strongly influenced by the R value, and a value of R > 7 is enough to reach the lowest value. From our measurements we infer that the formerly predicted value of R > 5 needed for a good magnetic and magnetoelastic response of the material must be actually regarded as the lowest limit for this parameter. In fact, we show that the demagnetizing factor N, rather than the length-to-width ratio R, is the parameter that governs the magnetoelastic performance of these strips.

Effective anisotropy field in the free layer of patterned spin-valve resistors

2011 ◽  
Vol 109 (10) ◽  
pp. 103904 ◽  
Author(s):  
Zhenghong Qian ◽  
Ru Bai ◽  
Changmao Yang ◽  
Qiliang Li ◽  
Yucheng Sun ◽  
...  
Keyword(s):  
Spin Valve ◽  
Anisotropy Field ◽  
Free Layer ◽  
Effective Anisotropy

scholarly journals Statistical Study of Effective Anisotropy Field in Ordered Ferromagnetic Nanowire Arrays

2007 ◽  
Vol 7 (1) ◽  
pp. 381-386 ◽  
Author(s):  
S. Zhao ◽  
L. Clime ◽  
K. Chan ◽  
F. Normandin ◽  
H. Roberge ◽  
...  
Keyword(s):  
Anisotropy Field ◽  
Nanowire Arrays ◽  
Anodized Aluminum ◽  
Local Anisotropy ◽  
Anodized Aluminum Oxide ◽  
Effective Anisotropy ◽  
Log Normal ◽  
Two Parameters ◽  
Ferromagnetic Nanowire ◽  
Magnetization Processes

Soft ferromagnetic nanowire arrays were obtained by electrodeposition of Co–Fe–P alloy into the pores of high quality home-made anodized aluminum oxide (AAO) templates. Bath acidity and current density were the two parameters used in order to tailor the orientation of local anisotropy axes in individual nanowires. In order to quantify the influence of the induced anisotropies on the magnetization processes in individual nanowires, the in-plane magnetization loops of the arrays are modeled as log-normal distributions of Stoner-Wohlfarth transverse magnetization processes. Using the lognormal mean parameter as an approximation for the saturation applied field of the array, we compute the effective anisotropy of the nanowires, which is found to increase with the pH of the electrodeposition bath.

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