The Influence of Substitution with Aluminum on the Field of Effective Magnetic Anisotropy and the Degree of Magnetic Texture of Anisotropic Polycrystalline Hexagonal Ferrites of Barium and Strontium for Substrates of Microstrip Devices of Microwave Electronics

2019 ◽  
Vol 48 (8) ◽  
pp. 582-588
Author(s):  
S. V. Shcherbakov ◽  
A. G. Nalogin ◽  
V. G. Kostishin ◽  
A. A. Alekseev ◽  
E. A. Belokon ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Hexagonal Ferrites ◽  
Magnetic Texture ◽  
Microwave Electronics ◽  
Effective Magnetic Anisotropy

scholarly journals Measurement of effective magnetic anisotropy field and ferromagnetic resonance bandwidth at ferromagnetic resonance frequency in magnetically uniaxial hexagonal ferrites

2019 ◽  
Vol 5 (1) ◽  
pp. 33-39
Author(s):  
Alexey S. Semenov ◽  
Aleksey G. Nalogin ◽  
Sergey V. Shcherbakov ◽  
Alexander V. Myasnikov ◽  
Igor M. Isaev ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Ferromagnetic Resonance ◽  
Transmission Lines ◽  
Anisotropy Field ◽  
Nominal Composition ◽  
Hexagonal Ferrites ◽  
Magnetic Texture ◽  
Measurement Results ◽  
Effective Magnetic Anisotropy ◽  
Ferromagnetic Resonance Frequency

In this work we have considered metrological problems and measurement of magnetic parameters and presented methods of measuring effective magnetic anisotropy field HAeff and ferromagnetic resonance bandwidth ∆H in magnetically uniaxial hexagonal ferrites in the electromagnetic microwave working frequency range. The methods allow measuring HAeff in the 10–23 and 28–40 kE ranges and ∆H in the 0.5–5.0 range. One method (suitable for wavelength measurements in free space in the 3-mm wavelength range) has been implemented for the 78.33–118.1 GHz range. The other method (based on the use of microstrip transmission lines) has been implemented for the 25–67 GHz range. The methods have been tested for polycrystalline specimens of hexagonal barium and strontium ferrites with nominal composition or complex substituted and having high magnetic texture. The measurement results have been compared with those obtained using conventional measurement methods and spherical specimens. Our methods prove to be highly accurate and reliable.

scholarly journals Influence of aluminum substitution on the fi eld of effective magnetic anisotropy and the degree of magnetic texture of anisotropic polycrystalline hexagonal ferrites of barium and strontium for substrates of microstrip devices of microwave electronics

2019 ◽  
Vol 21 (3) ◽  
pp. 166-174
Author(s):  
S. V. Shcherbakov ◽  
A. G. Nalogin ◽  
V. G. Kostishin ◽  
A. A. Alekseev ◽  
E. A. Belokon ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Anisotropy Field ◽  
Ceramic Technology ◽  
Preparation Technology ◽  
Magnetic Texture ◽  
Strontium Hexaferrites ◽  
Barium Hexaferrites ◽  
Microwave Electronics ◽  
Effective Magnetic Anisotropy ◽  
First Time

Abstract. In this paper, the effect of Al3+ ions substitutions on the value of the effective magnetic anisotropy field НАeff and the degree of magnetic texture f of the anisotropic polycrystalline hexagonal barium and strontium ferrites were studied. The samples were obtained by the ceramic technology method and the texture was formed by pressing in a magnetic field. The sample preparation technology presented in detail. The batches of barium hexaferrites were synthesized with the concentration of Al3+ ions: 0.9; 1.4; 2.5 and 2.6 formula units while strontium hexaferrites had Al3+ concentration of 0.1 formula units. It has been shown that by this technology barium and strontium hexaferrites with high value of (in range of 19—35 kOe) and with f = 80—83% could be obtained. The achieved values of НАeff and f could be sufficient for the production of substrates for microstrip microwave devices in millimeter−wave region.For the first time a raise in the degree of magnetic texture of polycrystalline barium hexaferrites with an increase of concentration of Al3+ ions were detected; a slight (5.5—5.8%) magnetic texture of isotropic strontium hexaferrites was also detected. The achieved results discussed in detail. For studied hexaferrites the mechanism of magnetic texture formation during the process of synthesis is proposed.

Exchange Bias in CrO2/Cr2O3 Bilayer Thin Films

2006 ◽  
Vol 45 ◽  
pp. 2528-2533 ◽  
Author(s):  
S. Srinath ◽  
N.A. Frey ◽  
H. Srikanth ◽  
G.X. Miao ◽  
A. Gupta
Keyword(s):  
Thin Films ◽  
Magnetic Anisotropy ◽  
Variable Thickness ◽  
Exchange Bias ◽  
Exchange Coupling ◽  
Hysteresis Loops ◽  
Anisotropy Constant ◽  
Effective Magnetic Anisotropy ◽  
Large Anisotropy

We have investigated the exchange bias in CVD grown epitaxial CrO2/Cr2O3 bilayer thin films using hysteresis loops and resonant RF transverse susceptibility. M-H loops indicated an enhanced coercivity without appreciable loop shift and the transverse susceptibility in CrO2/Cr2O3 bilayers revealed features associated with both the ferromagnetic and antiferromagnetic phases. In addition, TS yielded large anisotropy constant (Keff) values depending on the fraction of Cr2O3 present. The large anisotropy fields observed cannot be accounted for by the variable thickness of CrO2 alone and are indicative of possible exchange coupling between CrO2 and Cr2O3 phases that significantly affects the effective magnetic anisotropy.

Magnetism of Ultrathin Fe Films in the Vicinity of Transition from Ferromagnetism to Superparamagnetism

2006 ◽  
Vol 512 ◽  
pp. 165-170
Author(s):  
Yu Shiratsuchi ◽  
Yasushi Endo ◽  
Masahiko Yamamoto
Keyword(s):  
Magnetic Anisotropy ◽  
Growth Temperature ◽  
Magnetic State ◽  
Ferromagnetic State ◽  
Film Structure ◽  
Dominant Factor ◽  
Magnetic Anisotropy Energy ◽  
Flat Substrate ◽  
Effective Magnetic Anisotropy ◽  
Superparamagnetic State

We have investigated the magnetism of ultrathin Fe films grown on the inclined Al2O3(0001), especially, in the vicinity of ferromagnetic-superparamagnetic transition. In the transition region, the magnetic state of Fe films is the coexistence of ferromagnetism and superparamagnetism. The ratio of the components in ferromagnetic and superparamagnetic state is dependent on the growth temperature. For Fe grown on the flat substrate without the inclination, as the growth temperature increases, the ratio of the component in ferromagnetic state increases, reaches to the maximum and decreases again. On the presence of substrate inclination, the ratio of the component in ferromagnetic state increases, reaches to the maximum and decreases again. decreases monotonically with increasing growth temperature. We investigated the dominant factor of the complex magnetic state, and clarified that the complex magnetic state is dominated by the change of the film structure and the effective magnetic anisotropy energy.

Effective magnetic anisotropy of amorphous and nanocrystalline Fe71.5Al2Cu1Nb3Si13.5B9 alloy ribbon

2001 ◽  
Vol 89 (11) ◽  
pp. 6422-6425 ◽  
Author(s):  
G. R. Aranda ◽  
C. Miguel ◽  
P. Garcı́a-Tello ◽  
J. González
Keyword(s):  
Magnetic Anisotropy ◽  
Alloy Ribbon ◽  
Effective Magnetic Anisotropy
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