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We have studied the electron transport in SiO 2 (Co)/GaAs and SiO 2 (Co)/Si heterostructures, where the SiO 2 (Co) structure is the granular SiO 2 film with Co nanoparticles. In SiO 2 (Co)/GaAs heterostructures giant magnetoresistance effect is observed. The effect has positive values, is expressed, when electrons are injected from the granular film into the GaAs semiconductor, and has the temperature-peak type character. The temperature location of the effect depends on the Co concentration and can be shifted by the applied electrical field. For the SiO 2 (Co)/GaAs heterostructure with 71 at.% Co the magnetoresistance reaches 1000 (10 5 %) at room temperature. On the contrary, for SiO 2 (Co)/Si heterostructures magnetoresistance values are very small (4%) and for SiO 2 (Co) films the magnetoresistance has an opposite value. High values of the magnetoresistance effect in SiO 2 (Co)/GaAs heterostructures have been explained by magnetic-field-controlled process of impact ionization in the vicinity of the spin-dependent potential barrier formed in the semiconductor near the interface. Kinetic energy of electrons, which pass through the barrier and trigger the avalanche process, is reduced by the applied magnetic field. This electron energy suppression postpones the onset of the impact ionization to higher electric fields and results in the giant magnetoresistance. The spin-dependent potential barrier is due to the exchange interaction between electrons in the accumulation electron layer in the semiconductor and d-electrons of Co. Existence of spin-polarized localized electron states in the accumulation layer results in the temperature-peak type character of the barrier and the magnetoresistance effect. Spin injector and spin-valve structure on the base of ferromagnet / semiconductor heterostructures with quantum wells with spin-polarized localized electrons in the semiconductor at the interface are considered.

We report spatial localization of the effective magnetic field generated via the inverse Faraday effect employing surface plasmon polaritons (SPPs) at Au/garnet interface. Analyzing both numerically and analytically the electric field of the SPPs at this interface, we corroborate our study with a proof-of-concept experiment showing efficient SPP-driven excitation of coherent spin precession with 0.41 THz frequency. We argue that the subdiffractional confinement of the SPP electric field enables strong spatial localization of the SPP-mediated excitation of spin dynamics. We demonstrate two orders of magnitude enhancement of the excitation efficiency at the surface plasmon resonance within a 100 nm layer of a dielectric garnet. Our findings broaden the horizons of ultrafast spin-plasmonics and open pathways toward nonthermal opto-magnetic recording on the nanoscale.

The magnonic band gaps of the two types of planar one-dimensional magnonic crystals comprised of the periodic array of the metallic stripes on yttrium iron garnet (YIG) film and YIG film with an array of grooves was analyzed experimentally and theoretically. In such periodic magnetic structures the propagating magnetostatic surface spin waves were excited and detected by microstripe transducers with vector network analyzer and by Brillouin light scattering spectroscopy. Properties of the magnonic band gaps were explained with the help of the finite element calculations. The important influence of the nonreciprocal properties of the spin wave dispersion induced by metallic stripes on the magnonic band gap width and its dependence on the external magnetic field has been shown. The usefulness of both types of the magnonic crystals for potential applications and possibility for miniaturization are discussed.

Magnetoplasmonic crystals (MPC) composed of a 1D gold grating on top of a magnetic garnet layer made by a combined ion-beam etching technique are studied. We demonstrate that this method allows to make high-quality MPC. It is shown that MPC with a 30-40 nm thick perforated gold layer provides an effective excitation of two surface plasmon-polariton modes and several numbers of waveguide modes in the garnet layer. An enhancement of the transversal magneto-optical effect up to the value of 10(-2) is observed for all types of resonant modes, that propagate in the magnetic layer, due to magnetic-field control over the mode excitation which is promising for future photonic devices.