Improvement of microwave magnetic properties by inserting nonmagnetic layer

2017 ◽  
Vol 31 (02) ◽  
pp. 1750004
Author(s):  
Xiaoting Li ◽  
Chao An ◽  
Zhen Wang ◽  
Chunlong Xu ◽  
Gang Shi ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Anisotropy ◽  
Resonance Frequency ◽  
Exchange Coupling ◽  
Sandwich Structure ◽  
Anisotropy Field ◽  
Interface Energy ◽  
Coupling Energy ◽  
Radio Frequency Sputtering ◽  
Nonmagnetic Layer

Co/NM (nonmagnetic Ag and SiO2)/Co sandwich structure films with different thicknesses of NM were fabricated on Si(111) substrate via oblique radio frequency sputtering. With increasing thickness of nonmagnetic Ag [Formula: see text], in-plane magnetic anisotropy field [Formula: see text] initially increased from 100 Oe of [Formula: see text] nm to 220 Oe of [Formula: see text] nm, and then decreased when [Formula: see text] nm. Resonance frequency showed the same tendency with maximum 5.2 GHz when [Formula: see text] nm. Damp factor increased from 0.02 for [Formula: see text] for [Formula: see text] nm. The same result was observed in inserting oxide nonmagnetic SiO2 layer. This can be attributed to the competition between interface energy and exchange coupling energy.

PHASE EVOLUTION AND MAGNETIC PROPERTIES OF TbCu7-TYPE (Sm, Pr)Co7-xHfxMy (x = 0-0.5; y = 0-0.14) RIBBONS

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1663-1669 ◽  
Author(s):  
H. W. Chang ◽  
S. T. Huang ◽  
I. W. Chen ◽  
C. W. Chang ◽  
W. C. Chang
Keyword(s):  
Magnetic Properties ◽  
Magnetic Anisotropy ◽  
Exchange Coupling ◽  
Coupling Effect ◽  
Anisotropy Field ◽  
Phase Evolution ◽  
Phase Constitution ◽  
Melt Spun

The effects of Hf substitution and C content on the magnetic properties, phase evolution, and microstructure of melt spun ( Sm , Pr ) Co 7- x Hf x C y ( x = 0-0.5; y = 0-0.14) ribbons have been studied. A proper Hf substitution is helpful not only in stabilizing 1:7 phase but also in enhancing its magnetic anisotropy field. As a result, magnetic properties of B r = 6.4 kG , i H c = 7.3 kOe and ( BH ) max = 8.7 MGOe for SmCo 6.9 Hf 0.1 ribbons are obtained. Besides, a small amount of C addition in the ribbons could slightly modify phase constitution and effectively refine their microstructure to strengthen the exchange coupling effect between magnetic grains. Furthermore, a slight Pr substitution for Sm may further increase the magnetization and the magnetic properties of the ribbons. The optimal magnetic properties of B r = 7.1 kG , i H c = 8.5 kOe and ( BH ) max = 11.2 MGOe could be achieved for the directly quenched Sm 0.8 Pr 0.2 Co 6.9 Hf 0.1 C 0.12 ribbons.

HIGH MAGNETIC PROPERTIES OF TbCu7-TYPE MELT SPUN (Sm, Pr)Co7-xHfxCy RIBBONS

2008 ◽  
Vol 01 (03) ◽  
pp. 183-187 ◽  
Author(s):  
H. W. CHANG ◽  
S. T. HUANG ◽  
I. W. CHEN ◽  
C. W. CHANG ◽  
W. C. CHANG
Keyword(s):  
Magnetic Properties ◽  
Magnetic Anisotropy ◽  
Exchange Coupling ◽  
Coupling Effect ◽  
Anisotropy Field ◽  
Phase Evolution ◽  
Phase Constitution ◽  
Melt Spun

The effects of Hf substitution and C content on the magnetic properties, phase evolution and microstructure of melt spun ( Sm , Pr ) Co 7-x Hf x C y (x = 0–0.5; y = 0–0.14) ribbons have been studied. A proper Hf substitution is helpful not only in stabilizing 1:7 phase but also in enhancing its magnetic anisotropy field, as a result, magnetic properties of B r = 6.4 kG , i H c = 7.3 kOe and (BH) max = 8.7 MGOe for SmCo 6.9 Hf 0.1 ribbons are obtained. Besides, a small amount of C addition in the ribbons could slightly modify phase constitution and effectively refine their microstructure to strengthen the exchange coupling effect between magnetic grains. It leads to the improvement of the magnetic properties for SmCo 6.8 Hf 0.2 C 0.12 nanocomposites. Finally, a slight Pr substitution for Sm may further increase the magnetization and the magnetic properties, the optimal magnetic properties of B r = 7.1 kG , i H c = 8.5 kOe and (BH) max = 11.2 MGOe could be achieved for the directly quenched Sm 0.8 Pr 0.2 Co 6.9 Hf 0.1 C 0.12 ribbons.

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.

Magnetic Properties of Nanostructured Co-Based Alloys Produced by Dynamic Compaction and Plasma Spray Deposition

2012 ◽  
Vol 190 ◽  
pp. 192-195 ◽  
Author(s):  
L. Kuzovnikova ◽  
Elena A. Denisova ◽  
A. Kuzovnikov ◽  
Rauf S. Iskhakov ◽  
A. Lepeshev
Keyword(s):  
Magnetic Properties ◽  
Magnetic Anisotropy ◽  
Plasma Spray ◽  
Spray Deposition ◽  
Anisotropy Field ◽  
Dynamic Compaction ◽  
Magnetic Characteristics ◽  
Bloch Constant ◽  
Deposition Techniques ◽  
Ferromagnetic Resonance Linewidth

The bulk nanostructured Co-P alloys were prepared by dynamic compaction and a plasma spray deposition techniques. The magnetic characteristics, such as the saturation magnetization, M0, the Bloch constant, B, the local magnetic anisotropy field, Ha, the ferromagnetic resonance linewidth, ΔH, the coercivity, Hc, were investigated. A comparison between the magnetic properties of the Co-P alloys prepared by dynamic compaction and a plasma spray deposition techniques was carried out.

MICROSTRUCTURES AND MAGNETIC PROPERTIES OF COBALT THIN FILMS

2008 ◽  
Vol 22 (31) ◽  
pp. 3079-3086 ◽  
Author(s):  
DONGMAO JIAO ◽  
JIANGONG LI ◽  
XIA NI ◽  
XUDONG ZHANG
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Anisotropy Field ◽  
Network Analyzer ◽  
Soft Magnetic ◽  
Radio Frequency Sputtering ◽  
Cobalt Thin Films ◽  
Microwave Permeability ◽  
5 Ghz ◽  
Xrd And Tem

Cobalt thin films deposited by radio frequency sputtering were investigated. Microstructures of the Co films were analyzed by XRD and TEM. The results show that films microstructure varies with the variation of the sputter gas pressure P Ar . Magnetic properties measured by VSM show that all the films possess relatively high saturation magnetization 4πMs, and strong in-plane uniaxial magnetic anisotropy field Hk. Co films deposited below 0.3 Pa show soft magnetic properties and its microwave permeability was measured by vector network analyzer in the 0.1–5 GHz range.

Article

1998 ◽  
Vol 76 (11) ◽  
pp. 1595-1605
Author(s):  
B Heinrich ◽  
M Kowalewski ◽  
J F Cochran
Keyword(s):  
Magnetic Anisotropy ◽  
Exchange Coupling ◽  
Magnetic Energy ◽  
Interaction Model ◽  
Magnetic Films ◽  
Pair Interaction ◽  
Interface Energy ◽  
Interlayer Exchange Coupling ◽  
Interlayer Exchange ◽  
Interface Anisotropy

The interface magnetic energy in fcc Cu/Co/Cu(001) and Pd/Co/Pd(001) and the interlayer exchange coupling in bcc Fe/Cu/Fe(001) will be discussed and compared to recent theoretical models. The effect of interface magnetostriction and interface magnetic anisotropy will be described using a model proposed by Victora and MacClaren. The Victora-MacLaren theory of magnetic anisotropies is based on a generalized Néel pair interaction model that allows one to express the total interface energy in terms of the interface anisotropy and interface magnetoelastic contributions. It will be argued that the change in the sign of the interface anisotropy Ks as a result of replacing Cu atoms by Pd atoms is caused primarily by the enhanced role of the spin-orbit interaction in the Co-Pd pair interaction and in the tendency of Pd to acquire a significant magnetic moment in the proximity of ferromagnetic atoms. It will be shown that the interface lattice separations play an important role and the balance between these two magnetoelastic terms determines the total magnetoelastic contribution to the interface energy. The magnetoelastic interface contributions to Ks are +0.08 ergs/cm2 and +0.17 ergs/cm2 for the fcc Cu/Co/Cu(001) and Pd/Co/Pd(001) structures, respectively. The interlayer exchange coupling has been investigated in bcc trilayer structures Fe/Cu/XcCu1 - c/Cu/Fe where XcCu1 - c represents an alloyed atomic layer with X = Fe, Cr, Ag. The purpose of these studies was to determine the effect of foreign atoms inside a nonmagnetic spacer on the direct interlayer exchange coupling between the outside Fe layers mediated by the valence electrons of the Cu spacer. The experimental results will be compared with recent first principles calculations using the Layer Korringa-Kohn-Rostoker (LKKR) method. It will be shown that the local electron potential of the foreign atoms affects the spin transport across the spacer and is chiefly responsible for the observed behavior of the interlayer exchange coupling in Fe/Cu/XcCu1 - c/Cu/Fe. The interlayer e cxchange coupling depends very strongly on the magnetic state of the foreign atoms within the spacer. For foreign atoms with no long-range ferromagnetic order the exchange coupling is mainly affected by the 3d valence band electrons. Foreign atoms that are isoelectronic with the spacer atoms modify the strength of the exchange coupling only due to lattice relaxations that are associated with their atomic size.Key words: ultrathin metallic magnetic films, magnetic anisotropy, exchange interaction, Molecular Beam Epitaxy.

MAGNETIC PROPERTIES AND CRYSTAL STRUCTURE OF MELT SPUN Sm(Co, M)7 RIBBONS (M = Hf, V, Nb, andTa)

2009 ◽  
Vol 23 (31n32) ◽  
pp. 3707-3716 ◽  
Author(s):  
H. W. CHANG ◽  
C. C. HSIEH ◽  
Z. H. GUO ◽  
S. T. HUANG ◽  
W. C. CHANG
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
Magnetic Anisotropy ◽  
Anisotropy Field ◽  
Experimental Results ◽  
Element Substitution ◽  
Melt Spun

Magnetic properties and crystal structure of melt spun SmCo 7-x M x ( M = Hf , V , Nb , and Ta ; x = 0–0.3) ribbons have been investigated. The experimental results showed that not just Hf but also V , Nb and Ta prefer to occupy 2e site in the TbCu 7 structure and remarkably increase coercivity of the ribbons from 1.7 kOe for x = 0 to 10–12 kOe for x = 0.2, which would be due to the increase of magnetic anisotropy field by the element substitution. Furthermore, the effect of C addition on the magnetic properties and microstructure of melt spun Sm ( Co , M )7 ribbons were also studied. A small amount of C addition in the ribbons could effectively refine their microstructure, and leads to further improvement of the magnetic properties. The optimal magnetic properties of B r = 6.9 kG , i H c = 11.8 kOe and ( BH ) max = 10.6 MGOe were attained for SmCo 6.8 Hf 0.2 C 0.12 nanocomposites.

Dynamics and magnetic properties of NO molecules encapsulated in open-cage fullerene derivatives evidenced by low temperature heat capacity

2021 ◽  
Author(s):  
Yoji Horii ◽  
Hal Suzuki ◽  
Yuji Miyazaki ◽  
Motohiro Nakano ◽  
Shota Hasegawa ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Magnetic Properties ◽  
Low Temperature ◽  
Magnetic Anisotropy ◽  
Fullerene Derivatives ◽  
Molecular Cages ◽  
Temperature Heat ◽  
Low Temperature Heat Capacity

Heat capacity analyses revealed dynamics and magnetic anisotropy of NO molecules confined in molecular cages.

Rare earth permanent magnetic nanostructures: chemical design and microstructure control to optimize magnetic properties

2021 ◽  
Author(s):  
Junjie Xu ◽  
Kai Zhu ◽  
Song Gao ◽  
Yanglong Hou
Keyword(s):  
Magnetic Properties ◽  
Rare Earth ◽  
Exchange Coupling ◽  
Magnetic Nanostructures ◽  
Microstructure Control ◽  
Size And Shape ◽  
Chemical Design

The routes for the optimization of the magnetic properties of rare earth permanent magnetic nanostructures are discussed, i.e. the control of microstructure, such as size and shape as well as the exchange-coupling interactions.

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