N. N. Beletskii

Magnetoresistance of magnetic tunnel junctions with low barrier heights

The magnetoresistance of low-barrier magnetic tunnel junctions (MTJs) was studied within a two-band model of free electrons in ferromagnetic electrodes, taking into consideration image forces. For MTJs with an MgO insulator, explanations are given of the giant tunneling magnetoresistance (TMR) effect and the effect of increasing TMR as the width of the MgO barrier increases. It is shown that TMR and the electron current density through MTJs depend strongly on the dielectric constant of the MgO insulator. It is found that the TMR of low-barrier MTJs reaches a maximum at a particular value of the applied bias voltage. It is demonstrated that the electron current density through low-barrier MTJs can be high enough to switch the magnetization of a ferromagnetic electrode.

Electromagnetic waves in a defective periodic layered structure bordering upon a plasma-like medium

The periodic layered structures bordering plasma-like media are of lively interest at present [1,2]. In these structures there are new types of the surface electromagnetic waves which possess unusual properties. When a defective layer places into the periodic layered structure, the additional electromagnetic waves appear, which are called defective modes [3,4]. The dispersion curves of the defective modes are located in the forbidden gaps of the periodic layered structure. It should be expected that the surface electromagnetic waves and the defective modes interact with each other in a resonance way. Peculiarities of spectral and energy characteristics of TM-electromagnetic waves in the one-dimensional defective dielectric periodic layered structure bordering a plasma-like medium are studied in this paper. The effect of resonant interaction of plasma and defective modes has been predicted. Its dependence on structural and geometry parameters of the periodic layered medium is studied. The modification of the electromagnetic wave spectrum is analyzed as the location of the defective layer in the periodic layered medium changes. All the numerical calculations are carried out with regard to the frequency dispersion of the plasma-like medium. Moreover, we use non-dimensional values; that makes it possible to use our results in a widespread frequency range - from terahertz to optical ones.

Theoretical study of a non-stationary magnetic tunnel junction magnetoimpedance

Tunneling of electrons through non-stationary magnetic tunnel junctions (MTJs) in approximation of small amplitude of a variable electric field is investigated. High-frequency dependences of the active and reactive part of the electronic current density and magnetoimpedance of the non-stationary MTJs for parallel and antiparallel ferromagnetic electrode magnetizations are considered. The general properties of the non-stationary MTJs have been investigated. It is shown that the active part of the electronic current density through the non-stationary MTJs has oscillating character. The value of the active part of the electronic current density through the nonstationary MTJs can be negative or positive depending on the frequency region.

Magnetoresistance of two-barrier magnetic tunnel junctions

Magnetic tunnel junctions have high values of the tunneling magnetoresistance (TMR) at room temperature [1–6]. Due to this circumstance the magnetic tunnel junctions are widely used for creation of the random access magnetic memory and different sensors. At the same time the increase in TMR remains actual problem with regard to enhancement of spintronics device characteristics.

Interaction of plasma oscilations with charged particles intersecting a boundary of two media

In connection with the progress in modern technology of designing micro- and nanostructures the research on processes of interaction between electromagnetic oscillations and charged particles become topical. Results of this research are important both for comprehension of physics of surface phenomena occurring on media boundary and for many technical applications.

Quantizing of transition radiation of the surface polaritons by the charge, intersecting two-layer two-dimensional electron system, placed into strong magnetic field

The transition radiation of surface polaritons, which appears when the charge is moving through a homogeneous isotropic medium with dielectric constant /spl epsiv/, into which a two-layer 2D electron system (2DES), placed in a transverse quantizing magnetic field, is implanted, is theoretically investigated. The two layer 2DES consists of two GaAs infinitely deep quantum wells separated by an AlGaAs potential barrier of finite width and height. The quantizing magnetic field and the direction of the charge movement are perpendicular to the 2DES. The energy spectrum of the electrons in such a system is fully discrete, and this leads to stepwise dependencies of Landau level filling factor and Hall conductivity of the two-layer 2DES on on the magnetic field.