Study of electro-magneto-mechanical nanosystems based on antiferromagnetic materials and multiferroics

Starting from general principles of magnetic dynamics and laws of conservation we demonstrated a possibility of spin torque transfer in antiferromagnetic materials. We calculated the spectra and amplitude-frequency characteristics of spin excitations for different types of magnetic systems with complex structure in presence of spin – polarized current. It is shown that spin-polarized current induces motion of magnetic moments and appearance of macroscopic magnetization of an AFM layer. We propose new method of measurement of spintronic effects in AFM materials with help of effect of magnetoresistance which arises due to dynamic macroscopic magnetization.

We generalized the Brownian theory for the motion of AFM-vector in AFM nanoparticle and derived the kinetic equations for the description of magnetic dynamics for collinear antiferromagnet in the presence of noise. We also developed the methods for its solution in different regimes: precritical (close to equilibrium) and supercritical (in the vicinity stationary rotation). We developed the theory for description of magnetic dynamics of antiferromagnetic textures in the presence of high density current and demonstrated the possibility to control the domain-wall motion with the help of electric current. Dynamics of nanoelectromechanical system with an antiferromagnetic layer in the oresence of spin-polarized current was also studied. We predicted the spin-diode effect in antiferromagnetic systems which consists in rectification of alternating current at the expense of current-induced magnetoresistance oscillations. We studied the current-induced behavior of the magnetic structure in the amorphous wires in the presence of the external magnetic field, and mechanical stresses and revealed underlying physical mechanism responsible for a jump of magnetoresistance under external mechanical stresses.

We developed a model that describes shape effects in antiferromagnetic nanoparticles and synthetic multiferroics, in particular, in two types of multiferroics: antiferromagnet/ ferroelectric and antiferromagnet/ferromagnetic. The method of optimal control (fast switch) with the help of the combination of electric field and magnetic field is developed. This method opens a way to use such systems as memory elements.

We reviewed the current state of the field of spintronics based on the use of anti-ferromagnetic materials. The results obtained could be used for engineering of principally memory elements with higher (in comparison to ferromagnetic analogues) processing frequency and lower energy consumption.