Shinji Miwa

Electric fields at interfaces exhibit useful phenomena, such as switching functions in transistors, through electron accumulations and/or electric dipole inductions. We find one potentially unique situation in a metal-dielectric interface in which the electric field is atomically inhomogeneous because of the strong electrostatic screening effect in metals. Such electric fields enable us to access electric quadrupoles of the electron shell. Here we show, by synchrotron X-ray absorption spectrosco

Abstract Electric-field-induced control of magnetic properties at room temperature has attracted considerable attention owing to its significant potential for facilitating the construction of ultralow-power-consumption electric devices. Voltage-controlled magnetic anisotropy (VCMA) effect in ultrathin ferromagnetic metals has shown that the magnetization of nanomagnets can be controlled by electric fields in extremely short periods (down to 0.1 ns). The VCMA effect in metals can be the ultimate

In this study, voltage-controlled magnetic anisotropy (VCMA) in Fe|MgO tunnel junctions was investigated via the magneto-optical Kerr effect, soft x-ray absorption spectroscopy, and magnetic circular dichroism spectroscopy. The Fe|MgO tunnel junctions showed enhanced perpendicular magnetic anisotropy under external negative voltage, which induced charge depletion at the Fe|MgO interface. Despite the application of voltages of opposite polarity, no trace of chemical reaction such as a redox react

Magnetization, electrical conduction, and magnetoresistance (MR) of ${\mathrm{C}}_{60}\text{\ensuremath{-}}\mathrm{Co}$ nanocomposites, where Co nanoparticles are dispersed in ${\mathrm{C}}_{60}$ molecules, have been investigated over a wide temperature range and Co volume fraction. The ${\mathrm{C}}_{60}\text{\ensuremath{-}}\mathrm{Co}$ nanocomposites exhibit MR when the Co volume fraction is controlled in such a way that the conduction mechanism is dominated by tunneling of carriers between Co

Chirality-induced current-perpendicular-to-plane magnetoresistance (CPP-MR) originates from current-induced spin polarization in molecules. The current-induced spin polarization is widely recognized as a fundamental principle of chiral-induced spin selectivity (CISS). In this study, we investigate chirality-induced current-in-plane magnetoresistance (CIP-MR) in a chiral molecule/ferromagnetic metal bilayer at room temperature. In contrast to CPP-MR, CIP-MR observed in the present study requires

C60–Co nano-composites, in which Co nano-particles are embedded in C60 molecules, have been fabricated and a magnetoresistance (MR) ratio of 8% has been observed at T = 4.2 K. In addition, we have succeeded in observing a clear MR curve even at room temperature (RT). The MR effect is ascribed to magnetization of the Co nano-particles and spin-dependent transport in C60 molecules. This study directly indicates that RT operation of molecular spin devices can be realized.

Spin torque is a promising technique for flipping magnetic orientation in nanomagnets used in low-power computer memories, but accurately measuring this torque is difficult. A new experiment shows how ferromagnetic resonance can characterize spin-torque vectors at an Fe-MgO interface.