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In this report, current-induced spin–orbit torques (SOTs) in a permalloy (Py)/Pt/Co tri-layer system are investigated. In addition to the conventional SOTs generated from the spin Hall effect in the Pt layer, we observed a distinct existence of unconventional SOT acting on the in-plane magnetized Py layer in which the polarity of SOT reverses with the magnetization of perpendicularly magnetized Co. From its symmetry and experimental verifications, we conclude that this unconventional SOT, especially the damping-like torque term, originates from the additional spin current generated by the spin–orbit precession effect at the Pt/Co interface. Moreover, we reveal that the polarity of this SOT strongly depends on the interface structure of the ferromagnetic material/non-magnetic metal (NM), which can be controlled by the choice of NM material. The interface structure dependence shows a consistent result with first principle calculations of the spin–orbit precession effect that were previously reported. Our findings not only broaden the origin of the current-induced SOT but also pave the way for the design of high-efficient SOT-based devices.

The dielectric and magnetic properties of electric double layer (EDL) capacitor structures with a perpendicularly magnetized Pt/Co/Pt electrode and an insulating cap layer (MgO) are investigated. An electric field is applied through a mixed ionic liquid/MgO barrier to the surface of the top Pt layer, at which the magnetic moment is induced by the ferromagnetic proximity effect. The basic dielectric properties of the EDL capacitor are studied by varying the thickness of the MgO cap layer. The results indicate that the capacitance, i.e., the accumulated charge density at the Pt surface, is reduced with increasing the MgO thickness. From the MgO thickness dependence of the capacitance value, the effective dielectric constant of the ionic liquid is evaluated. Almost no electric field effect on the magnetic moment, the coercivity, or the Curie temperature is confirmed in the top Pt layer with the thickness of 1.3 nm, regardless of the presence or absence of the MgO cap layer, whereas the a clear change in the magnetic moment is observed when the top Pt layer is replaced by a Pd layer of 1.7 nm.

Electron optical system is constructed in order to obtain small angle diffraction and Lorentz deflection of electrons at the order of down to 10-6 radian in the reciprocal space. Long-distance camera length up to 3000 m is achieved in a conventional transmission electron microscope with LaB6 thermal emission type. The diffraction pattern at 5 × 10-6 radian is presented in a carbon replica grating with 500 nm lattice spacing while the magnetic deflection pattern at 2 × 10-5 radian is exhibited in Permalloy elements. A simultaneous recording of electron diffraction and Lorentz deflection is also demonstrated in 180 degree striped magnetic domains of La0.825Sr0.175MnO3.

Abstract  We perform large-scale numerical simulations on the non-equilibrium superconducting dynamics after a neutron capture at the superconducting transition edge in MgB2 by solving the time-dependent Ginzburg-Landau equation coupled with the Maxwell and the heat diffusion equations. The simulations are carried out under the current-biased condition in order to explain experimental results made in the JAEA reactor JRR-3, and the time scale of the obtained voltage signal is found to be almost consistent with the experiments. Moreover, the time evolution of the voltage signal is connected with that of the spatial profile of the superconducting order parameter. [ABSTRACT FROM AUTHOR]

We fabricated a solid-state capacitor on an organic flexible substrate, which has an ultra-thin ferromagnetic Co electrode with a HfO2 dielectric layer formed by atomic layer deposition. Tensile stress was applied parallel to the capacitor plane. The breakdown strain monotonically increases with a reduction in HfO2 layer thickness. From the sheet resistance measurement, strain endurance up to 1.5% is realized in the capacitor with 10 nm thick HfO2. A magnetic anisotropy of the Co layer is controllable by applying voltage between the Co and counter electrode. The modulation efficiency of the voltage-controlled magnetic anisotropy is almost independent of the strain. [ABSTRACT FROM AUTHOR]

A numerical method applicable to the analysis of the multi-scale electromagnetic (EM) excitations in intrinsic Josephson junctions (IJJs) is presented. Using this method, we investigate the EM wave emission from the IJJs observed in Bi2Sr2CaCu2O8 mesas. The IJJs have three length scales that are greatly different in magnitude, i.e. the distance between superconducting layers (d [?] 10 [?] 3 um), the Josephson length (lJ [?] 1 um) and the c-axis penetration depth (lc [?] 102 um). The EM field excited in the IJJs generally shows spatial variation of these three length scales at the same time. In our numerical method the coupled dynamical equations for the phase differences and the EM field can be solved simultaneously in all the scales in the whole space composed of the IJJs and the surrounding vacuum. We clarify that the spatial symmetry of the EM field excited at the resonance with the p-cavity-mode is different from that with the 2p-cavity-mode. The strong EM wave emission originating from the p-cavity-mode resonance takes place in the region where the uniform branch becomes unstable in the I-V characteristics. [ABSTRACT FROM AUTHOR]