Spin-resolved photoemission (SRPES) experiments have attracted much attention to investigate not only the spin dependent electronic structures of magnetic thin films and surfaces, but also those of non-magnetic materials, e.g. Rashba spin-split surface electronic states and edge states of topological insulators, etc. To show the utilities of SRPES, we show spin-resolved photoemission spectra of Fe thin films grown on Rh(001) surface and Rashba spin-split surface electronic states of √ 3 × √ 3 BiAg/Si(111). We also present our newly developed SRPES spectrometer equipped with VLEED-type spin detector, which achieves 100 times larger efficiency than those of conventional ones.
Understanding of the mechanism of current-induced magnetic domain wall (DW) motion is essential for practical use of this phenomenon. Recent experiment has revealed that in perpendicularly magnetized Co/Ni nano-wire the threshold current density for DW motion is determined by ‘intrinsic pinning’ and it is independent of the DW pinning strength. Besides, the velocity of DW motion has been shown to be independent of external magnetic fields. In this review, recent progress of the study on the current-induced DW motion is described.
With the increase in the recording density of hard disk drives, the narrower magnetic pole and read-sensor widths in writing and reading heads are required, and techniques used for the magnetic behavior analysis in a nanoscale area is essential. The observation of the in-plane domain structure of the writer pole for a perpendicular recording (PMR) head was performed by electron holography in order to elucidate the mechanism of the pole erasure originating from the instability of the magnetic domain state. The results revealed that the stability of the domain structure is strongly related to the domain wall trapping, and the pole erasure can be suppressed by realizing the stable domain structures. With respect to a current perpendicular to plane (CPP)-giant magneto-resistive (GMR) head, which has been promising candidates of a next-generation reading head element, the insertion of non-magnetic materials, such as Cu, between the ferromagnetic pinned and free layers is known to increase the MR ratio. For realizing the practical use of the CPP-GMR head, effects of the insertion of materials on the increase in the MR ratio were investigated by X-ray magnetic circular dichroism (XMCD). The results revealed that XMCD is a powerful technique to obtain information on electronic states and magnetic moments with the help of the theoretical electronic band calculation. The potential application of secondary cantilever resonance magnetic force microscopy and spin-polarized scanning electron microscope to the in-situ magnetic imaging of PMR heads will be also discussed.
The method for in-situ measurements of the effective pumping speed of high vacuum pumps and the sensitivity of ionization gauges has been developed. The measurement system consists of the gas introduction device with the standard conductance element, and the pumping system with the conductance modulation method. The effective pumping speed of turbomolecular pump, the inverse of the correction factor of ionization gauges, and the effective accommodation coefficient of the spinning rotor gauge were measured by using fifteen kinds of gas species including water vapor. The uncertainty of the measurement was evaluated to be around ten percent. The obtained results are consistent with the conventional literature values within the measurement uncertainties.
An elemental species that bonds oxide and metal at the interface is crucial to the electric properties of the electronic devices. We have developed a numerical formula for predicting a stable interface bonding species at a metal/alumina interface in our previous study. In this study, we extend this numerical formula for predicting interface bonding between alumina and aluminum-containing metals. The effectiveness of the extended formula was examined by experimental results in references. It was revealed that the prediction by the formula agreed with the results reported in the references. According to the formula, O-terminated interface between pure metal (M) and alumina can be switched to Al-termination by alloying the pure metal with Al metal. The formula uses only basic quantities of pure elements and the formation enthalpy of oxides. Therefore it can be applied for most of metals in the periodic table and is useful for material screening in interface modification.
Fine structures with a Co-lined barrier layer, Co/TaN and Co/Ru/TaN, were experimentally fabricated by high-vacuum magnetron sputtering, and copper-filling tests were performed with the supercritical carbon dioxide method. As a result, the complete copper filling of all trenches with a width of about 80 nm and an aspect ratio (AR) of four was accomplished for Co/Ru/TaN but not for Co/TaN. The experimental results also show that complete copper filling was possible even for trenches with a width of about 30 nm and an AR of nine for Co/Ru/TaN. The reasons for these results are explained by the dependence of Cu(111) texture on the underlying Co stack.