Potential barrier for spin-polarized electrons induced by the exchange interaction at the interface in the ferromagnet/semiconductor heterostructure

Abstract

We have calculated the exchange interaction between electrons in the accumulation electron layer in the semiconductor near the interface and electrons in the ferromagnet in the ferromagnet/semiconductor heterostructure. It is found that the exchange interaction forms the potential barrier for spin-polarized electrons. The barrier height strongly depends on the difference of chemical potentials between the semiconductor and the ferromagnet. The maximum of the potential barrier height on the temperature dependence is due to the existence of localized electron states in the accumulation layer. In the framework of the developed theoretical model, the injection magnetoresistance effect observed in semiconductor/granular film heterostructures with ferromagnetic metal nanoparticles is explained. A spin filter on the base of granular film/semiconductor/granular film heterostructures operated at room temperature is proposed.

Giant magnetoresistance in semiconductor/granular film heterostructures with cobalt nanoparticles

“…If the accumulation layer does not contain localized states, the magnitude of W sharply falls. Dependencies of W on the difference of chemical potentials ∆µ and temperature dependencies are presented in [40].…”

“…The IMR effect has a temperature-peak type character and its location can be shifted by the applied electrical field. High values of the IMR effect in SiO 2 (Co)/GaAs heterostructures and the temperature-peak type character are explained in section 3 by the theoretical model of a magnetic-field-controlled avalanche process provided by electrons passed through the spindependent potential barrier in the accumulation layer at the interface [40]. In section 4 we consider FM / SC heterostructures with quantum wells with spin-polarized localized electrons in the SC at the interface as efficient room-temperature spin injectors and magnetic sensors.…”

Magnetic-field-induced photocurrent in metal-dielectric-semiconductor heterostructures based on cobalt nanoparticles SiO2(Co)/GaAs

“…The largest 70 magneto-resistance coefficient was observed for the SiO 2 (Co)/GaAs heterostructure with Co concentration of 60 at.%, therefore it was used in experiments on the magnetic-field-induced photocurrent [16]. The hysteresis curve has a small coercivity due to direct exchange in clasters of 100 The injection magneto-resistance effect and decrease of the current flowing in the SiO 2 (Co)/GaAs structure are described by the model based on the spindependent potential barrier and on the avalanche suppression in the magnetic field [8,17]. According to the model, accumulation electron layer in GaAs is formed in the interface region and the potential barrier is localized at a certain 105 distance from the semiconductor/film interface.…”

Spin wave spectroscopy and microwave losses in granular two-phase magnetic nanocomposites

“…The spin-polarized accumulation electron layer in semiconductor/insulator films with ferromagnetic metal nanoparticles has been reported recently. 49 The characteristics of these accumulation layers depend strongly on the values of the chemical potentials of the different phases and on their corresponding volume fractions. Accumulation layers can play a role on the interaction between nanoparticles ͑via the long range Ruderman-KittelKasuya-Yosida ͑RKKY͒-type exchange interaction͒ and on magnetic relaxation.…”