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Finemet-type nanocrystalline soft magnetic alloys have shown attractive magnetic properties[1-3]. However, due to the relatively low Curie point of the residual amorphous matrix, they cannot be used at high temperature[4-5]. Partial substitution of Co for Fe was carried out to meet the desire for high temperature magnetic properties[6-7]. When Co was added to the FeSiBNbCu alloys, although the Curie...
Recently, there is an increasing interest in exploiting antiferromagnet (AFM) as an active element in spintronic devices arising from its advantages of negligible shape anisotropy and good thermal stability as compared to its ferromagnet (FM) counterpart. To reap these benefits of AFM, however, one must find a viable way to obtain sizable output signal from AFM and an efficient mechanism for reorienting...
Recently, the exchange bias (EB) phenomenon in the ferromagnet/antiferromagnet (FM/AFM) bilayer and its inborn instability effect, i.e., training effect [1], have attracted much attention for its great technological importance in spintronic devices. Usually, the study of training effect is performed by continuously recording the exchange field (HE) and the coercivity (HC) after measuring an entire...
Electromagnetic limited-angle torque motors (LATMs) which have a limited angular movement less than 180 degrees are widely applied in industry, particularly for positioning tasks. Compared with common rotating motors, LATMs have many advantages such as simple structure, high reliability, and uncomplicated control mode. In general, radial-flux permanent-magnet LATMs have two conventional types which...
Electric Machine is an energy conversion device, which realizes the electrical energy and mechanical energy convert to each other through electromagnetic power or electromagnetic torque. Electromagnetic torque is an important medium for this conversion progress. Thus accurate estimation or model of electromagnetic torque is desired for designing and analyzing the electric machines. Furthermore electromagnetic...
Permanent magnet synchronous motor (PMSM) has been widely used in household appliances, medical instruments and vehicles. Electromagnetic interference (EMI) is a challenging problem for PMSM drive system fed by pulse width modulation (PWM) inverter because of the reason that EMI noise generates undesirable influences on control system such as communication errors, degraded equipment performance and...
PMSMs with concentrated windings gain more and more interests due to the very short end winding and advantages in the production process, for which they are desirable for wind power generations, electric vehicles and torque propulsion and so on [1]. However, concentrated windings produce a rich spectrum of flux density harmonics, which rotate asynchronously with respect to the rotor, inducing eddy...
The basic magnetic properties of patterned magnetic film have been attracting much interests due to their potential applications in magnetic random access memory (MRAM) and ultrahigh-density data storage devices [1], [2], [3]. Their magnetic properties closely depend on the size, shape and inter-element interactions, which have been reported extensively in the past 20 years. However, their researches...
The FeRh alloy has been the subject of many experimental and theoretical studies over the last fifty years.[1-3] This interest is primarily due to the observation that the near-equiatomic phase of FeRh possesses a chemically ordered CsCl-type structure which exhibits an abrupt antiferromagnetic (AFM) to ferromagnetic (FM) transition with heating to a transition temperature of around 350K in the bulk...
Recently light induced effects in magnetic nanostructures have attracted much interest. [1-5] Indeed it provides a new way to control and manipulate magnetization and spin currents, which are key elements of spin-based electronics [4]. For example, all optical helicity dependent magnetization switching have been demonstrated and could be applied for magnetic recording [5].
The drive system of induction motor is a complex nonlinear system. Several studies have been performed on the saddle-note bifurcation of induction motor ignoring iron loss. However, little work has been done on the system with iron loss. In this paper, we will analyze this problem with Lyapunov stability theory. By the analysis and simulation verification, the following conclusions are obtained: The...
Permanent magnet synchronous machines (PMSM) have high torque density, efficiency, power factor and so on compared with other type of machines. PMSMs can be separated into traditional well-known distributed wounded (DW) machines and fractional slot concentrated winding (FSCW) machines [1]. FSCW machines own low cogging torque, compact structure, high power density, and convenient fabrication, etc...
Soft magnetic alloys have been widely applied to modern technology devices, such as transformer cores, choke coils and inductive devices. Magnetic field annealing can induce an uniaxial magnetic anisotropy Ku [1-4] so as to improve the soft magnetic properties of alloys for the purpose of coping with different application requirements. So far, FeCo-based nanocrystalline alloys have been explored increasingly...
Soft ferromagnetic amorphous ribbons are widely used for a wide range of applications, including high-frequency transformers and magnetic sensors. The recent discovery of a so-called giant mag-netoimpedance (GMI) effect in these alloys has made them very attractive candidates for making highly sensitive magnetic sensors [1]. GMI effects have been reported in Co-based amorphous ribbons owing to the...
Finemet alloys exhibit superior soft magnetic properties with high initial permeability (μ), low coercivity and low core loss, which attracted a great deal of attention [1]. However, their application is limited to the temperature close to the Curie point of an amorphous matrix, Tcam, because the intergranular magnetic coupling is usually interrupted by the paramagnetic amorphous matrix. As the result,...
Half-metallic magnetite with high spin polarization at the Fermi level has always been an ideal candidate for spin dependent transport study [1, 2], and understanding of the magnetic transportation property of Fe3O4 becomes a critical issue for its future applications in spintronics. Generally the resistance of Fe3O4 decreases (negative MR) when applied in a magnetic field as the conduction in Fe3...
FSCW SPM machines (SPP <1/2, such as 10-pole/12-slot), own outstanding constant power ability [1], although it was regard widely that only IPM machines can be flux-weakened deeply. SPM machines are considered as a favorite candidate for electric propulsion and vehicle application, in order to take their other advantages, such as convenient fabrication, and good controllability [2]. The constant...
Since the magnetic anisotropy of ferromagnetic (FM) films on semiconductor substrates has promising application for spintronics, it has stimulated extensive studies in the last two decades [1]. Remarkably, amorphous FM alloy films also exhibit uniaxial magnetic anisotropy (UMA) in the film plane when deposited on semiconductor substrates, e.g. CoFeB/GaAs (001) [2]. Although several models, including...
Spintronics strives to revolutionize conventional electronics by integrating magnetic materials with semiconductor devices, such as the spin field effect transistor (SFET)[1], which not only improve the capabilities of electronic devices, but develop new functionalities. For electrodes of spin injection and detection in SFET device, half metallic Fe3O4 is an attractive candidate because its high Curie...
Design and experimental study of a wide-band U-band gyrotron travelling wave tube (gyro-TWT) amplifier are presented. The interaction circuit is constructed by periodic loaded dielectric, which provided required loss for stable operation. Potential oscillations are effectively suppressed. The U-band gyro-TWT is zerodriven stable at the operating points. A saturated peak power of 158 kW was measured...
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