Oleg N. Mryasov

Spin-dependent tunnelling in magnetic tunnel junctions

The phenomenon of electron tunnelling has been known since the advent of quantum mechanics, but continues to enrich our understanding of many fields of physics, as well as creating sub-fields on its own. Spin-dependent tunnelling (SDT) in magnetic tunnel junctions (MTJs) has recently aroused enormous interest and has developed in a vigorous field of research. The large tunnelling magnetoresistance (TMR) observed in MTJs garnered much attention due to possible applications in non-volatile random-access memories and next-generation magnetic field sensors. This led to a number of fundamental questions regarding the phenomenon of SDT. In this review article we present an overview of this field of research. We discuss various factors that control the spin polarization and magnetoresistance in MTJs. Starting from early experiments on SDT and their interpretation, we consider thereafter recent experiments and models which highlight the role of the electronic structure of the ferromagnets, the insulating layer, and the ferromagnet/insulator interfaces. We also discuss the role of disorder in the barrier and in the ferromagnetic electrodes and their influence on TMR.

Temperature-dependent magnetic properties of FePt : Effective spin Hamiltonian model

A model of magnetic interactions in the ordered ferromagnetic FePt is proposed on the basis of first-principles calculations of non-collinear magnetic configurations and shown to be capable of explaining recent measurements of magnetic-anisotropy energy (MAE). The site (Fe,Pt) resolved contributions to the MAE have been distinguished with small Fe easy-plane and large Pt easy-axis terms. This model has been tested against available experimental data on the temperature dependence of MAE showing scaling of uniaxial MAE (K1(T)) with magnetization (M(T)) K1(T) ~ M(T)γ characterized by the unusual exponent of γ = 2.1. It is shown that this unusual behavior of the FePt can be quantitatively explained within the proposed model and originates from an effective anisotropic exchange mediated by the induced Pt moment. The latter is expected to be a common feature of 3d-5d(4d) alloys having 5d/4d elements with large spin-orbit coupling and exchange-enhanced Stoner susceptibility.

Ternary site preference energies, size misfits and solid solution hardening in NiAl and FeAl

The electronic structure of NiAl and FeAl doped with Ti, V, Cr, Mn, Fe, Co, Y, La and Zr additions in both sublattices has been investigated with the local density linear muffin-tin orbital (LMTO) method. The peculiarities of chemical bonding for both undoped and with some ternary additions in NiAl and FeAl were analyzed using the LMTO-Green function method. The preferred sites for ternary additions were found and the sensitivity of site preference energies to crystal relaxation effects was investigated. It was shown that the relaxation has an elastic nature and the values of size misfit parameters for substitutional impurities were estimated. The experimental data concerning solid solution hardening were reanalyzed and the additional contributions to hardening besides the conventional size misfit mechanism were shown to be of importance for Ti ternary additions.

Spin-orbit coupling induced anisotropy effects in bimetallic antiferromagnets: A route towards antiferromagnetic spintronics

Magnetic anisotropy phenomena in bimetallic antiferromagnets

Reversible Control of Co Magnetism by Voltage-Induced Oxidation

{\text{Mn}}_{2}\text{Au}

“All-Heusler alloy” current-perpendicular-to-plane giant magnetoresistance

and MnIr are studied by first-principles density-functional theory calculations. We find strong and lattice-parameter-dependent magnetic anisotropies of the ground-state energy, chemical potential, and density of states, and attribute these anisotropies to combined effects of large moment on the

The effect of Coulomb correlation and magnetic ordering on the electronic structure of two hexagonal phases of ferroelectromagnetic YMnO3

\text{Mn}\text{ }3d

Atomic and electronic structure of the CoFeB∕MgO interface from first principles

shell and large spin-orbit coupling on the

Development of glue-type potentials for the Al-Pb system: Phase diagram calculation

5d

Exchange spring structures and coercivity reduction in FePt∕FeRh bilayers: A comparison of multiscale and micromagnetic calculations

shell of the noble metal. Large magnitudes of the proposed effects can open a route towards spintronics in compensated antiferromagnets without involving ferromagnetic elements.