Efforts have been ongoing to establish superconducting spintronics utilizing ferromagnet/superconductor heterostructures. Previously reported devices are based on spin-singlet superconductors (SSCs), where the spin degree of freedom is lost. Spin-polarized supercurrent induction in ferromagnetic metals (FMs) is achieved even with SSCs, but only with the aid of interfacial complex magnetic structures, which severely affect information imprinted to the electron spin. Use of spin-triplet superconductors (TSCs) with spin-polarizable Cooper pairs potentially overcomes this difficulty and further leads to novel functionalities. Here, we report spin-triplet superconductivity induction into a FM SrRuO3 from a leading TSC candidate Sr2RuO4, by fabricating microscopic devices using an epitaxial SrRuO3/Sr2RuO4 hybrid. The differential conductance, exhibiting Andreev-reflection features with multiple energy scales up to around half tesla, indicates the penetration of superconductivity over a considerable distance of 15 nm across the SrRuO3 layer without help of interfacial complex magnetism. This demonstrates potential utility of FM/TSC devices for superspintronics.

Direct electron transfer (DET)-type bioelectrocatalytic waves of bilirubin oxidase (BOD)-catalyzed O 2 reduction and [NiFe] hydrogenase (H 2 ase)-catalyzed H 2 oxidation are very small and un-detectable using glassy carbon (GC) electrodes, respectively; however, clear catalytic waves are observed when the enzymes are adsorbed on Ketjen black-modified GC (KB-GC) electrodes, in which KB provides mesopores for DET-type bioelectocatalysis. To explain the phenomena, we focus on the curvature effect of mesoporous structures on long range electron transfer kinetics and simulate steady-state voltammograms catalyzed by model redox enzymes adsorbed with a random orientation on planar and mesoporous electrodes based on a three-dimensional model. In the simulation, we assume a spherical enzyme with a radius of r, an active site located at a certain distance from the center of the enzyme, and a spherical pore with a radius of R p in mesoporous electrodes in which the enzyme is trapped and adsorbed. The simulation reveals that mesoporous electrodes provide platforms suitable for DET-type bioelectrocatalysis of enzymes when R p becomes close to r. Such curvature effects of mesoporous electrodes become especially notable for larger sized enzymes. Furthermore, the simulation reproduces the experimental data of BOD-and H 2 asecatalyzed DET-type waves by considering the crystal structures of the enzymes. This work will open a route to improve the kinetic performance of the DET-type bioelectrocatalysis that has become very important in its practical application to a variety of bioelectrochemical devices.

To investigate the effect of mesoporous media as electrodes for the observation of a noncatalytic Faradaic current of redox proteins adsorbed on an electrode (i.e., redox peaks in adsorption voltammetry), we propose a simulation model with randomly oriented redox proteins to obtain adsorption voltammograms. Furthermore, we compare the simulated currents of redox proteins adsorbed on planar and mesoporous electrodes. In this model, a redox protein is postulated as a sphere with the active site located at a certain distance from the center of the protein. For a mesoporous electrode, a spherical pore with a radius of R p is assumed. When R p is close to the radius of the protein, a redox peak is obtained even when the active site is located at a great distance from the protein surface; however, the peak is not observed for a planar electrode. This is ascribed to an increase in the number of proteins with orientations suitable for electron transfer because of the curvature effect of the pore. This work indicates that mesoporous media with appropriate pore sizes will provide suitable platforms for several redox proteins to produce observable Faradaic currents.

Effects of the electrode poential on the activity of an adsorbed enzyme has been examined by using copper efflux oxidase (CueO) as a model enzyme and by monitoring direct electron transfer (DET)-type bioelectrocatalysis of oxygen reduction. CueO adsorbed on bare Au electrodes at around the point of zero charge (E(pzc)) shows the highest DET activity, and the activity decreases as the adsorption potential (E(ad); at which the enzyme adsorbs) is far from E(pzc). We propose a model to explain the phenomena in which the electrostatic interaction between the enzyme and electrodes in the electric double layer affects the orientation and the stability of the adsorbed enzyme. The self-assembled monolayer of butanethiol on Au electrodes decreases the electric field in the outside of the inner Helmholtz plane and drastically diminishes the E(ad) dependence of the DET activity of CueO. When CueO is adsorbed on bare Au electrodes under open circuit potential and then is held at hold potentials (E(ho)) more positive than E(pzc), the DET activity of the CueO rapidly decreases with the hold time. The strong electric field with positive surface charge density on the metallic electrode (σ(M)) leads to fatal denaturation of the adsorbed CueO. Such denaturation effect is not so serious at E(ho)<

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