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Magnetic iron oxide nanoparticles have attracted broad interests in many biomedical areas, such as magnetic resonance imaging (MRI) contrast enhancement, magnetic hyperthermia, magnetic bio-sensing, and cell labeling [1]. To avoid nanoparticle aggregation and enhance their colloidal stability, carboxylate surfactants are widely used as coating materials to form steric repulsions between nanoparticles...
The magnetic properties and the magnetocaloric effect (MCE) of Er4PdMg compound have been investigated by magnetization and heat capacity measurements. The compound undergoes a second order magnetic phase transition from a paramagnetic to a ferromagnetic state at Curie temperatures of TC ∼ 16 K. For a field change of 0–7 T, the maximum values of magnetic entropy change (−ΔSMmax) and adiabatic temperature...
Magnetic property of nanoparticles is intimately related with their structure, size, morphology, and magnetic anisotropy. In recent years, some non-spherical iron oxide nanoparticles are found to have superior performance in biomedical applications compared to their spherical counterparts. For example, iron oxide nanocubes was reported to have higher magnetic heating efficiency in hyper-thermia, and...
Diamond-like carbon (DLC) films which contain a mixture of sp2 and sp3 hybridizations are widely used as a protective layer against wear and corrosion in hard disk drives (HDDs) due to their outstanding mechanical and tribological properties such as high hardness, low friction coefficient and excellent chemical durability [1]. The typical thickness of DLC film in HDD is approximately 1-2nm. For such...
An improved approach for predicting the armature reaction field in Permanent-Magnet AC (PMAC) machines is presented, and eddy current reaction is take into account. Winding configuration of PM machines could be various, such as concentric winding or lap winding, integral or fractional slot winding, distributed or concentrated winding, single-layer or double-layer winding. Starting with the field produced...
In a magnetic tunnel junction (MTJ) device, the potential barrier height of the barrier layer, in presence of a bias voltage or an external magnetic field, can be affected by defects present in the barrier layer or at the barrier layer/ferromagnetic (FM) layer interfaces of the device. The defects may have structural as well as magnetic origin. Fluctuations of such defects (with a time scale that...
In the case of III-V dilute magnetic semiconductors (DMS), the holes from Mn doping are known to mediate the ferromagnetic interaction among the Mn ions. Through modulation of the hole density, electrostatic gating has been shown to significantly alter the magnetic properties of (III, Mn)V films[1-3]. Here we demonstrate the manipulation of the magnetism of DMS (Ga, Mn)As. Mn-doped GaAs thin films...
Wireless power transfer (WPT) via magnetic resonant coupling (MRC) proposed by a research team of Massachusetts Institute of Technology (MIT) in 2007 [1], has caused increasing interest in research and development of WPT technology. The WPT coils which are operated with the same resonance frequency are the core of the MRC-WPT. Until now, there have been two basic structures to implement MRC-WPT system...
Recently more and more attention has been paid to the application of flux weakening of a permanent magnet synchronous machine (PMSM). In this paper, many rotor configurations of the PMSM that are suitable for flux weakening operation were reviewed. A new stator design with shunt teeth has been studied by magnetic circuit analysis and finite element analysis. The new design and the conventional design...
The power density of permanent magnet synchronous motor (PMSM) can be improved by increasing the input current density. However, the output power of the motor will not grow linearly with the rising input current. Because the motor would be confronted with the influence of armature reaction, stator core magnetic saturation and thermal dissipation.
Hybrid nanostructure can inherit the physiochemical properties of its individual components to realize its multi-functionality. The coupling of plasmonic effect of gold nanoparticles with magnetic properties of iron oxide nanoparticles has shown great promise as bi-functional agents allowing simultaneous magnetic resonance imaging (MRI)/ computed tomography (CT) imaging and magnetic/photonic thermal...
Ferromagnetic electrodes with perpendicular magnetic anisotropy (PMA) have been extensively studied because of the outstanding performance in applications. [1] To obtain high tunneling magnetoresistance (TMR), researchers have put efforts to realize PMA with Co-based full-Heusler alloy films with MgO barrier. However, the lattice mismatch between MgO and full-Heusler alloy leads to a rapid TMR reduction...
As the development of the information technology and intelligence of the society, wireless sensor networks have been widely applied in many fields of life and production [1-3]. In many practical engineering applications, it is often expected to be able to conduct real-time monitoring to the inner situation of some media. One ideal way to fulfill such objectives is to embed the wireless sensors inside...
Radio-frequency and microwave devices based on ferromagnetic nanowires have recently attracted a lot of research interests, because the phenomenon of ferromagnetic resonance (FMR) of nanowires can raise the working frequency of these devices beyond 20 GHz [1-3]. A typical way of tuning the FMR frequency of nanowires is to apply an external magnetic field; however, this way is not practical in micro-device...
Planar switched reluctance motors (PSRMs) have the merits of simple structure, low cost, low heat loss, high precision, ease of manufacture, and strong adaptability of harsh environment, which directly transform the mechanical energy to electromagnetic energy available to planar motions without mechanical transmissions. Therefore, PSRMs are an attractive candidate in high-precision two-dimensional...
We have been developing a kind of micro spectrometer with 64 pixels GaAs-based quantum dots-in-well in double barrier photodetector linear array. The novel photodetector array has a specific inner multiplication at extremely weak illumination environment at low bias voltage. High current gains are achieved and accompanied by extremely low dark currents. The photoelectric response spectrum of the photodetector...
A two-dimensional ferromagnet is an interesting system both for basic understanding of magnetism and for spintronic applications. However, making such a system is not easy as ferromagnetism becomes more and more unstable with reducing the thickness of a ferromagnet. For example, in oxide systems such as SrRuO3, La1−xSrxMnO3, etc, ferromagnetism is lost around the thickness of a few unit cells [1,...
In order to increase recording density in hard disk drives (HDDs), thermal flying height control (TFC) sliders have recently been introduced to reduce the head-disk spacing to less than 2 nm [1]. Slider/disk contacts increase with a decrease in flying height, and consequently, the likelihood of disk failure due to slider/disk contacts increases [2]. Contacts occur predominantly between the thermal...
Rare-earth cobalt nanocrystalline alloys, especially SmCo5 and SmCo7, have raised great research interests due to their various attractive characteristics, such as huge magnetocrystalline anisotropy, high coercivity, high Curie temperature, and appreciable energy product. It is commonly acknowledged that the coercivity mechanism of these compounds is determined predominately by the pinning of domain...
The type of magnetic multilayers and heterostructures is extremely rich, including magnetic metal/ nonmagnetic metal, magnetic metal/nonmagnetic insulator, ferromagnet/antiferromagnet etc[1]. Special attentions have been paid to interfaces because it correlates to electrical and magnetic properties, particularly exchange bias (EB) which usually occurs in ferromagnetic/ antiferromagnetic system[2]...
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