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Electric field effects on magnetism in metals have attracted widespread attention, but the microscopic mechanism is still controversial. We experimentally show the relevancy between the electric field effect on magnetism and on the electronic structure in Pt in a ferromagnetic state using element-specific measurements: x-ray magnetic circular dichroism (XMCD) and x-ray absorption spectroscopy (XAS). Electric fields are applied to the surface of ultrathin metallic Pt, in which a magnetic moment is induced by the ferromagnetic proximity effect resulting from a Co underlayer. XMCD and XAS measurements performed under the application of electric fields reveal that both the spin and orbital magnetic moments of Pt atoms are electrically modulated, which can be explained not only by the electric-field-induced shift of the Fermi level but also by the change in the orbital hybridizations.

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We report that the superconducting critical magnetic field can be nonreciprocal under a bias of an electric current in a superconducting [Nb/V/Ta] n superlattice without a center of inversion. The critical magnetic field showed a clear difference between positive and negative magnetic fields. Furthermore, the magnitude relation between the positive and negative critical magnetic fields is reversed when the direction of the electric current is reversed. Our findings indicate that the superconducting gap can be anisotropic by the application of an electric current.

All-optical helicity dependent switching (AO-HDS), deterministic control of magnetization by circularly polarized laser pulses, allows to efficiently manipulate spins without the need of a magnetic field. However, AO-HDS in ferromagnetic metals so far requires many laser pulses for fully switching their magnetic states. Using a combination of a short, 90-fs linearly polarized pulse and a subsequent longer, 3-ps circularly polarized pulse, we demonstrate that the number of pulses for full magnetization reversal can be reduced to four pulse pairs in a single stack of Pt/Co/Pt. The obtained results suggest that the dual-pulse approach is a potential route towards realizing efficient AO-HDS in ferromagnetic metals.

Electric field effect on magnetism is an appealing technique for manipulating the magnetization at a low cost of energy. Here, we show that the local magnetization of the ultra-thin Co film can be switched by just applying a gate electric field without an assist of any external magnetic field or current flow. The local magnetization switching is explained by the nucleation and annihilationof the magnetic domain through the domain wall motion induced by the electric field. Our results lead to external field free and ultra-low energy spintronic applications.

A creep motion of the magnetic domain wall (DW) in a perpendicularly magnetized Co wire, where the DW energy is artificially varied by applying a sloped electric field, is studied. Under the sloped electric field and a constant external magnetic field, the DW velocity gradually changes according to the position of the wire owing to the spatially varying DW energy. Although the sloped DW energy can be a source to drive a DW, no clear electric-field-induced DW motion is observed, most likely because the effective magnetic field induced by the sloped electric field is very small in the present system.

There is a need to control magnetic properties at a desired location in a magnetic film towards a realization of fundamental devices, such as domain wall logic or magnonic applications. Here, we demonstrate the formation of a magnetic domain structure at a desired location in a Pt/Co film, using electrical gating with a meshed gate electrode and sweeping the applied magnetic field. As the magnetic properties can be changed by modulating the electron density at the surface of the Co layer, this method in principle provides higher speed and power-efficient operation in inducing a nanoscale domain structure or in configuring a volatile magnonic crystal.