Minori Goto 교수

The fabrication of a circuit capable of stabilizing skyrmions is important for the realization of micro- to nano-sized skyrmion devices. Ultralow power Brownian computers have been theoretically proposed and are a promising example of a skyrmion-based device. However, such devices have not been realized as it would require skyrmions to be stabilized and easily movable within a circuit. Skyrmion circuits fabricated by the etching of ferromagnetic films often decrease the dipolar magnetic field st

Spin-polarized radio frequency (RF) currents and RF-Oersted fields resonantly excite a magnetic vortex core confined in a micron-scale soft magnetic disk. In this study, we measured the rectifying voltage spectra caused by the anisotropic magnetoresistance oscillation due to the gyration of the vortex with different polarity and chirality. The measured spectra are presented such that we can determine the vortex properties and strength of the spin torques and Oersted field accurately and directly

Bolometers are rectification devices that convert electromagnetic waves into direct current voltage through a temperature change. A superconducting bolometer has a responsivity of approximately 10⁶-10⁷ V/W under cryogenic temperatures at infrared wavelengths; however, no devices have realized such a high responsivity in the sub-GHz frequency region. We describe a spin bolometer with a responsivity of (4.40 ± 0.04) × 10⁶ V/W in the sub-GHz region at room temperatu

A magnetic vortex core confined in a micron-scale magnetic disk is resonantly excited by both spin-polarized rf current and rf field. We found that rectifying voltage spectra caused by the resonance of vortex core are dependent not only on the core polarity, but also the chirality. These experimental results can be explained by analytically calculating the anisotropic magnetoresistance effect induced by the motion of the vortex core.

Antivortex creation in a cross-shaped wire was demonstrated by using magnetoresistance and magnetic force microscopy measurements. The magnetization process was stochastic and exhibited a wide variety of magnetoresistance curves. By developing a conventional method, we have achieved electrical determination criteria to distinguish antivortex creation from many other magnetization states. The electrical criteria provide a simple method without large-scale apparatus and promote further experiments

Abstract We present electric field modulation of tunneling anisotropic magnetoresistance (TAMR) in MnIr|MgO|Ta tunnel junctions. TAMR enables direct observation of the antiferromagnetic spin direction at the MnIr|MgO interface. We found that the shape of magnetoresistance (MR) curve can be modulated by an electric field, which can be explained by electric field modulation of the interfacial magnetic anisotropy at MnIr|MgO.

Skyrmions are topological spin textures that exhibit Brownian motion in solids. They have attracted increasing research interest in terms of realizing a device that utilizing stochastic behavior and investigating new physical phenomena. However, skyrmions that exhibit Brownian motion are sensitive to changes in magnetic properties and are easily affected by aging variation. For instance, although skyrmions appear in a sample immediately after fabrication, they sometimes disappear after few weeks

We demonstrate the current-driven resonance of a single antivortex core confined in a cross-shaped Ni81Fe19 wire. The antivortex core dynamics can be excited purely by spin transfer torque; therefore, it is significant to understand the current-induced magnetization dynamics. The antivortex core resonance can be measured from the frequency dependence of a rectified voltage generated by an alternating current application. We found that the resonance frequency and peak amplitude greatly depend on