scholarly journals In-Plane Current Induced Nonlinear Magnetoelectric Effects In Single Crystal Films of Barium Hexaferrite

2021 ◽  
Author(s):  
Maksym Popov ◽  
Igor Zavislyak ◽  
Hongwei Qu ◽  
A. M. Balbashov ◽  
M. R. Page ◽  
...  
Keyword(s):  
Electric Power ◽  
Uniaxial Anisotropy ◽  
Barium Hexaferrite ◽  
Anisotropy Field ◽  
Current Data ◽  
Single Domain ◽  
Magnetoelectric Effects ◽  
Hexagonal Axis ◽  
Crystal Films ◽  
Device Applications

Abstract This report is on the observation and analysis of nonlinear magnetoelectric effects (NLME) for in-plane currents perpendicularly to the hexagonal axis in single crystals and liquid phase epitaxy grown thin films of barium hexaferrite. Measurements involved tuning of ferromagnetic resonance (FMR) at 56-58 GHz in the multidomain and single domain states in the ferrite by applying a current. Data on the shift in the resonance frequency with input electric power was utilized to estimate the variations in the magnetic parameter that showed a linear dependence on the input electric power. The NLME tensor coefficients were determined form the estimated changes in the magnetization and uniaxial anisotropy field. The estimated NLME coefficients for in-plane currents are shown to be much higher than for currents flowing along the hexagonal axis. Although the frequency shift of FMR was higher for the single domain resonance, the multi-domain configuration is preferable for device applications since it eliminates the need for a large bias magnetic field. Thus, multidomain resonance with current in the basal plane is favorable for use in electrically tunable miniature, ferrite microwave signal processing devices requiring low operating power.

Heteroepitaxial Barium Hexaferrite Films on (111) Magnesium Oxide Substrates

2000 ◽  
Vol 623 ◽  
Author(s):  
Steven A. Oliver ◽  
Soack Dae Yoon ◽  
Izabella Kozulin ◽  
Ming Ling Chen ◽  
Xu Zuo ◽  
...  
Keyword(s):  
Uniaxial Anisotropy ◽  
Pulsed Laser ◽  
Barium Hexaferrite ◽  
Anisotropy Field ◽  
Biaxial Stress ◽  
Narrow Linewidth ◽  
X Ray Diffraction ◽  
X Ray ◽  
Millimeter Wavelength ◽  
Oxide Substrates

AbstractHigh quality films of barium hexaferrite (BaFe12O19) were deposited by pulsed laser ablation onto MgO (111) substrates. In contrast to previous films deposited onto c-plane sapphire (Al203), these films were expected to have compressive biaxial stress, and indeed showed no indications for either cracking or delamination to a film thickness of 32 νm. All films were found to be highly c-axis textured by both x-ray diffraction measurements and magnetization results. The saturation magnetization (4πMs = 4.2 kG) and uniaxial anisotropy field (HA = 16 kOe) values for these films approach bulk values. Ferrimagnetic resonance measurements on a calcined 3 μm thick film show a narrow linewidth (ΔH ∼ 100 Oe) for the uniform resonance mode. The properties of these films approach those required for self-biased millimeter wavelength devices.

Magnetic Study on Divalent Ion Substituted Barium Hexaferrites

2021 ◽  
Vol 410 ◽  
pp. 714-719
Author(s):  
Denis Vinnik ◽  
Santhoshkumar Mahadevan ◽  
Puneet Sharma
Keyword(s):  
Magnetic Properties ◽  
Solid State ◽  
Barium Hexaferrite ◽  
Anisotropy Field ◽  
Magnetic Interaction ◽  
Ceramic Method ◽  
Saturation Magnetisation ◽  
State Ceramic ◽  
Saturation Remanence ◽  
Substituted Barium Hexaferrite

Magnetic properties of Co, Ni and Zn substituted barium hexaferrite (BaM) samples prepared by solid state ceramic method were studied. Saturation magnetisation were found higher for Zn-substituted BaM, whereas, coercivity is higher for Co2+ and Ni2+ ion substituted samples. Anisotropy field for all substituted samples was calculated by the law of approaching saturation. Remanence, squareness and thermomagnetic plot suggest Zn2+ ions restricts the magnetic interaction of various sites in BaM.

Growth of high quality single‐domain single‐crystal films of PbTiO3

1994 ◽  
Vol 65 (9) ◽  
pp. 1106-1108 ◽  
Author(s):  
Z. Li ◽  
C. M. Foster ◽  
D. Guo ◽  
H. Zhang ◽  
G. R. Bai ◽  
...  
Keyword(s):  
Single Crystal ◽  
Single Domain ◽  
High Quality ◽  
Single Crystal Films ◽  
Crystal Films

scholarly journals Dynamics of Magnetization in Multilayer TbCo / FeCo Structures under the Influence of Femtosecond Optical Excitation

2019 ◽  
Vol 7 (3) ◽  
pp. 50-58 ◽  
Author(s):  
N. A. Ilyin ◽  
A. A. Klimov ◽  
N. Tiercelin ◽  
P. Pernod ◽  
E. D. Mishina ◽  
...  
Keyword(s):  
Easy Axis ◽  
Uniaxial Anisotropy ◽  
Anisotropy Field ◽  
Optical Excitation ◽  
Spin Precession ◽  
Heat Diffusion ◽  
Easy Magnetization ◽  
Test Beam ◽  
Magnetic Subsystem ◽  
Hard Axis

The need to study ultrafast processes in magnetism is due to the prospects for creating ultrafast magnetic recording and ultrafast spintronic devices. In order to excite the magnetic subsystem femtosecond optical pulses are used. The excitement is manifested as in spin precession. In metals, the material is heated first due to significant optical absorption, and significant Joule losses occur. The most important task is to search for materials in which spin processes are excited without heating. Obvious candidates are weakly absorbing materials, such as ferrite garnets. However, the range of such materials and the range of their functionality are limited.The purpose of this work is to study the dynamics of systems with nonthermal mechanisms of spin precession excitation. Such excitation is possible in ferromagnetic / antiferromagnetic heterostructures with exchange interaction, provided that the recombination time of photocarriers is shorter than the time of heat diffusion. Multilayer TbCo / FeCo structures of the near IR range were investigated for a femtosecond optical pulse. The spin dynamics are compared with the direction of the wave vector of the exciting pulse along and perpendicular to the axis of easy magnetization of the structures (“easy axis” and “hard axis” geometry, respectively). It is shown that in case of “easy axis” geometry the determinative mechanism is the thermal interaction. When the system is exposed to an excitation pulse, this mechanism leads to a decrease in the projection of magnetization on the direction of propagation of the test beam. In case of “hard axis” geometry, the magnetization turns to the magnetic field at the initial stage. Then it precesses and relaxes to an equilibrium angular orientation. Such dynamics indicate a rapid recovery of the uniaxial anisotropy field after laser irradiation. The presented results demonstrate an ultrafast change in the magnetic anisotropy induced during the fabrication of the heterostructure under study, which may be of interest for optical control of the orientation of the magnetization.

scholarly journals Studi Pola Arus Bocor Isolator Keramik Selama Waktu Pemakaian 24 Jam

2020 ◽  
Vol 3 (3) ◽  
Author(s):  
Dini Fauziah ◽  
Waluyo Waluyo ◽  
Ismail Muhammad Khaidir
Keyword(s):  
Ambient Temperature ◽  
Electric Power ◽  
Leakage Current ◽  
Distribution System ◽  
Power Transmission ◽  
Current Data ◽  
Electric Power System ◽  
Leakage Currents ◽  
Ceramic Insulator ◽  
Distribution System Reliability

ABSTRAK Isolator merupakan komponen yang penting dijaga keandalannya dalam sistem transmisi dan distribusi tenaga listrik. Isolator rentan mengalami kegagalan akibat lingkungan, karena terpapar langsung kondisi dimana isolator tersebut terpasang. Salah satu jenis isolator yang sering digunakan adalah bahan keramik, dimana memiliki kelebihan diantaranya kekuatan mekanik yang cukup handal. Namun kekurangan isolator jenis ini adalah sifat permukaannya yang hidrofilik, yaitu mudah menyerap air sehingga bila digunakan pada kelembaban tinggi cenderung memicu timbulnya arus bocor. Arus bocor merupakan parameter penting pada isolator karena sering menjadi penyebab kegagalan isolator. Untuk mengetahui seberapa besar pengaruh kondisi lingkungan terhadap arus bocor, dilakukan pengujian terhadap isolator keramik dalam waktu 24 jam. Data arus bocor diambil setiap 3 jam untuk melihat perubahannya berdasarkan perubahan kelembaban, dan suhu lingkungan. Hasilnya didapat bahwa semakin tinggi kelembaban udara, dan semakin rendah suhu lingkungan maka arus bocor semakin tinggi. Hasil penelitian ini dapat dijadikan acuan untuk mengantisipasi kegagalan isolator keramik akibat arus bocor sehingga keandalan sistem tenaga listrik dapat terjaga. Kata kunci: Isolator keramik, Lingkungan, Kelembaban, Suhu. ABSTRACT Isolator is an important component that must be maintained to keep electric power transmission and distribution system reliability. Isolators are susceptible to failure due to the environment, because they are directly exposed to conditions where the insulator installed. Ceramic insulator is one type of isolator that is often used, which has advantages including mechanical strength that is quite reliable. However, the lack of this type of isolator is its hydrophilic surface, which is easy to absorb water so that when used at high humidity tends to trigger a leakage current. Leakage current is an important parameter in an insulator because it can be a cause due to insulator failure. To find out how environmental conditions impact on leakage currents along day, a ceramic isolator is tested within 24 hours. Leakage current data is taken every 3 hours to see the changes based on changes in humidity, and ambient temperature. The result is the higher humidity of the air, and the lower ambient temperature, can make insulator leakage current rise up. The results of this study can be used as a reference to anticipate the failure of ceramic insulators due to leakage currents so that the reliability of the electric power system can be maintained. Keywords: ceramic insulator, environtment, humidity, temperature.

Probing Arrays of Circular Magnetic Microdots by Ferromagnetic Resonance

2008 ◽  
Vol 8 (6) ◽  
pp. 2811-2826 ◽  
Author(s):  
G. N. Kakazei ◽  
T. Mewes ◽  
P. E. Wigen ◽  
P. C. Hammel ◽  
A. N. Slavin ◽  
...  
Keyword(s):  
Ferromagnetic Resonance ◽  
Quantitative Description ◽  
Uniaxial Anisotropy ◽  
Anisotropy Field ◽  
Iterative Solution ◽  
Wave Dispersion ◽  
Square Lattice ◽  
Rectangular Lattice ◽  
Force Microscopy ◽  
Good Agreement

X-band ferromagnetic resonance (FMR) was used to characterize in-plane magnetic anisotropies in rectangular and square arrays of circular nickel and Permalloy microdots. In the case of a rectangular lattice, as interdot distances in one direction decrease, the in-plane uniaxial anisotropy field increases, in good agreement with a simple theory of magnetostatically interacting uniformly magnetized dots. In the case of a square lattice a four-fold anisotropy of the in-plane FMR field Hr was found when the interdot distance a gets comparable to the dot diameter D. This anisotropy, not expected in the case of uniformly magnetized dots, was explained by a non-uniform magnetization m(r) in a dot in response to dipolar forces in the patternedmagnetic structure. It is well described by an iterative solution of a continuous variation procedure. In the case of perpendicular magnetization multiple sharp resonance peaks were observed below the main FMR peak in all the samples, and the relative positions of these peaks were independent of the interdot separations. Quantitative description of the observed multiresonance FMR spectra was given using the dipole-exchange spin wave dispersion equation for a perpendicularly magnetized film where in-plane wave vector is quantized due to the finite dot radius, and the inhomogenetiy of the intradot static demagnetization field in the nonellipsoidal dot is taken into account. It was demonstrated that ferromagnetic resonance force microscopy (FMRFM) can be used to determine both local and global properties of patterned submicron ferromagnetic samples. Local spectroscopy together with the possibility to vary the tip-sample spacing enables the separation of those two contributions to a FMRFM spectrum. The global FMR properties of circular submicron dots determined using magnetic resonance force microscopy are in a good agreement with results obtained using conventional FMR and with theoretical descriptions.

Effect of stress on exchange coupling field, coercivity, and uniaxial anisotropy field of NiFe/NiO bilayer thin films

1997 ◽  
Vol 70 (5) ◽  
pp. 664-666 ◽  
Author(s):  
De-Hua Han ◽  
Jian-Gang Zhu ◽  
Jack H. Judy ◽  
John M. Sivertsen
Keyword(s):  
Thin Films ◽  
Exchange Coupling ◽  
Uniaxial Anisotropy ◽  
Anisotropy Field ◽  
Coupling Field
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