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This study demonstrated our successful visualization of the non-volatile analog resistance changes in a metal/oxide/metal sandwiched structure. The resistance change has been intensively studied and practically utilized in the IoT devices, such as resistive random access memory and resistive analog neuromorphic device. Real-time observation technique of device operation (operando observation technique) by laser-excited photoemission electron microscopy (Laser-PEEM) enabled the visualization. The operando observation showed that the signal intensity of Laser-PEEM changed over the whole of the device area with the analog resistance changes. It is sufficiently certain that the change in signal is due to the creation and repair of oxygen vacancies throughout the device area, because the signal intensity reflects the number of electrons near the Fermi level. Considering the results of this study, we conclude that the analog resistance change depends on the device structure and oxygen vacancy concentration in metal/oxide junctions, which are controllable determinants of the device operation. [ABSTRACT FROM AUTHOR]

The perpendicular magnetic properties of CoCr films on GaAs substrates are investigated by magneto-optical Kerr-effect measurements. The direct deposition of the CoCr film on the GaAs substrate did not show any perpendicular properties and the thickness dependence of the hysteresis loop and the magnetic force microscopy showed that the onset thickness of ferromagnetism was 6.5nm.

A new study investigates the Schottky barrier height of MnSb(001)/GaAs(111)B diodes.

We present the results of a systematic change of magnetic-domain structure of epitaxial MnAs film on GaAs(001) in a temperature range of 17.5[degrees]C-45[degrees]C by magnetic-force microscopy (MFM). As temperature decreases, the small localized domains are formed and gradually collapse to the stripe domains. Finally, at 17.5[degrees]C the whole film turns to be a nearly single magnetic domain including only a small fraction of the nonferromagnetic [beta]-MnAs phase, as directly confirmed in the MFM experiment. Index Terms--Magnetic domains, magnetic-force microscopy (MFM), magnetic thin films.

We have observed the magnetic domain evolution under an external magnetic field in an epitaxial MnAs film on GaAs(001) by magnetic force microscopy. Owing to the strain involved, the ferromagnetic [alpha]-MnAs and the paramagnetic [beta]-MnAs phases coexist as self-aligned stripes at room temperature. It was found that a complex magnetic domain structure appeared in the ferromagnetic [alpha]-phase region at the demagnetized state (H = 0 Oe). As the magnetic field increased, the magnetic domain structure was gradually changed, and reached a completely saturated state at H = 600 Oe. Especially, at H = 300 Oe, the observed magnetic domain wall distribution is well matched with the topographical shape. Index Terms--Magnetic domains, magnetic force microscopy, magnetic thin films.

The epitaxial growth of zinc-blende CrAs/GaAs multilayer with thick zinc blende-CrAs layer in total is examined. CrAs and GaAs do not grown epitaxially when the thickness of CrAs layer is greater than 2 ML and the thickness of GaAs layer is smaller than 2 ML.

The electronic structures and magnetic properties of GaAs-based ferromagnetic semiconductor with a high Cr content, (Ga, Cr)As are discussed. A flat surface is observed in (Ga, Cr)As thin film up to the Cr content of 0.18 whereas larger roughness of the film is observed when the Cr content exceeds 0.20.

The fabrication and magnetotransport properties of nanoscaled clusters of manganese antimonide (MnSb) grown on sulfur-passivated GaA(001) substrates by molecular-beam-epitaxy (MBE) are reported. Magnetotransport measurement is thought to be a powerful method to elucidate magnetic behaviors of nanoscaled magnetic dots.

We investigated the dependence of the performance of magnetic force microscopy (MFM) on magnetic coating materials by using carbon nanotube (CNT) probes. The magnetic structures of CNT-MFM probes with CoFe(80:20), CoFe(30:70), and CoCr(80:20) coatings were essentially the same in the simulations, but their magnetic properties, such as stability after magnetic reversal, varied slightly in the experiments. It was found that a larger saturation magnetic moment (Ms) is of advantage for attaining high spatial resolution. Although the distinction was hard to see in the MFM images, the experiments and simulations showed that CNT probes coated with high Ms materials gave stronger perturbations to soft magnetic materials than probes coated with low Ms materials. [ABSTRACT FROM AUTHOR]

Nanocrystalline Pr2Co14B-based films are deposited on two types of substrates at 600 °C by radio frequency magnetron sputtering. All samples are composed of a hard magnetic phase Pr2Co14B and a small amount of a soft magnetic phase Co3B. The film sputtered on the thermally oxidized silicon wafer has a more dispersed distribution of Co3B and a smaller average grain size of Pr2Co14B than that deposited on alumina substrates; therefore, the former film shows a stronger intergrain exchange coupling action (IECA) than the latter film. In addition, the coercivity (8.6 kOe) and ratio (0.68) of remanence to saturation magnetization of the film sputtered on thermally oxidized silicon wafers are considerably higher than those (0.4 kOe and 0.56) of the film deposited on alumina substrates. In the case of the film sputtered on alumina substrates, the size of most magnetic domains is comparable to the average grain size of magnetic phases, implying the occurrence of a weak IECA. However, in the case of the film sputtered on thermally oxidized silicon wafers, the size of most magnetic domains is considerably larger than the mean grain size of magnetic phases, indicating the occurrence of a strong IECA. The effect of the IECA on the coercivity of specimens is determined by analyzing the temperature dependence of coercivity in the framework of a nucleation model. [ABSTRACT FROM AUTHOR]

A 100-nm-thick Fe50Pt50 film with high coercivity was fabricated by magnetron sputtering. On introducing a Cr top/bottom layer, the ordering temperature (Tor) of the film decreased considerably from 500 to 380 °C. On introducing both Cr top/bottom layer and a 0.2-nm-thick Cu interlayer, the Tor decreased even further to 340 °C. During the annealing process, the number of Cr atoms diffused into the Fe50Pt50 layer increased. This increased the Fe diffusivity, lowering the Tor in the process. The diffusion of the additive and the effects of annealing were verified by selected-area electron diffraction observations and by investigating the temperature dependence of the magnetization. The superlattice structure of the ordered Fe50Pt50 film containing Cr and Cu additives was confirmed by the transmission electronic microscopy. Because of the Cr and Cu additives, the average grain size in the ordered Fe50Pt50 film increased slightly; however, the coercivity of the ordered Fe50Pt50 film is improved considerably. [ABSTRACT FROM AUTHOR]

The crystal orientation of zinc-blende MnTe thin films grown by molecular beam epitaxy on GaAs substrates was investigated. The results showed that the structure and stoichiometry of the substrate surfaces had a significant influence on the orientation and the twin formation of the thin films. Preheating treatments at 580 degrees celsius produced a reconstruction pattern on the surface.

The formation, as well as the structure-property relationship of the various nanocrystalline [Pr.sub.2][Co.sub.14]B-based hard magnetic films are discussed. The variations observed in the magnetic domains and the inergrain exchange coupling action observed in the different films spluttered on different surfaces are also explained.

The article studies the enhancement in ordering of [Fe.sub.50][Pt.sub.50] film caused by Cr and Cu additives using transmission electronic microscopy. Results reveal that uperlattice structure of the ordered of [Fe.sub.50][Pt.sub.50] film containing Cr and Cu additives was confirmed by the transmission electronic microscopy.

Brillouin light scattering (BLS) is used for examining the dynamic magnetic properties of epitaxial MnAs thin films. The thermal effects results in a significant damping of the spin-wave BLS spectrum along with an increasing excitation laser power.

Reports on the preparation of single crystal epitaxial films of CdTe on sapphire and gallium arsenide substrates by the ionized cluster beam deposition method. Information on photoluminescence studies and discussions.