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Pavel A. Vorobyev

Publications and source records attributed to Pavel A. Vorobyev.

4 recordsLinked to original sources

Quantum encoding of structured light into in-plane topological spin textures

Structured light offers a powerful means of controlling light-matter interactions through multiple tunable optical degrees of freedom. Using micromagnetic simulations, we investigate the nucleation of asymmetric bimerons and antibimerons by pulsed Laguerre-Gaussian optical vortices in chiral ferromagnetic thin films with $C_{nv}$ and $D_{2d}$ symmetries, respectively. For optical vortices with orbital angular momentum (OAM) $|m|=1$, circularly polarized beams deterministically nucleate a single bimeron or antibimeron via the interplay of spin angular momentum, OAM, and magnetic chirality, whereas linearly polarized beams produce textures whose topological charge directly follows the OAM ($Q=m$). Optical vortices with OAM $|m|>1$ nucleate clusters and other configurations composed of multiple spin textures, whose morphology and topological charge depend sensitively on the optical quantum numbers and pulse parameters. These findings reveal a route to topology-selective writing through the encoding of optical quantum numbers into distinct in-plane topological magnetic states.

cond-mat.mes-hall↗

Asymmetric Antibimerons: Statics and Dynamics

Nontrivial topological spin textures, such as magnetic skyrmions, are of great interest due to their potential use as information carriers in spintronic memory and logic. Here, we theoretically predict an asymmetric antibimeron (AAB) -- a topological texture in an in-plane magnetized chiral ferromagnet with $D_{2d}$ symmetry, which has yet to be observed experimentally. We show that AABs can be stabilized by an anisotropic interfacial Dzyaloshinskii-Moriya interaction, characteristic of materials with $D_{2d}$ symmetry. Using energy considerations, we explain the origin of its asymmetric shape, composed of an antivortex and a crescent-shaped vortex with opposite core polarizations. Furthermore, we demonstrate that AABs of opposite topological charge can coexist within the same ferromagnetic film, in contrast to skyrmions in out-of-plane magnetized systems. Employing micromagnetic simulations and an analytical approach based on an extension of Thiele's equation to a system of two elliptic merons comprising the AAB, we are able to describe the current-driven dynamics of AABs. In particular, we show that AAB collisions enable controlled manipulation of the system's topological charge. Our findings shed light on fundamental understanding of asymmetric topological magnetic solitons and provide a roadmap for their experimental observation in in-plane magnetized ferromagnets.

cond-mat.mes-hall↗

Topology-constrained spin-wave modes of asymmetric antibimerons and their clusters

Collective modes are a defining signature of coupled degrees of freedom, forming a bridge between understanding of interactions in condensed-matter systems and emergent functionality. Topological magnetic textures provide a natural platform to realize and control such collective modes at the nanoscale. Here we theoretically identify and characterize low-energy collective spin-wave excitations of isolated asymmetric antibimerons and their clusters in ultrathin ferromagnetic films. We demonstrate that an isolated asymmetric antibimeron supports a discrete spectrum of localized modes, reflecting its internal degrees of freedom. When multiple asymmetric antibimerons form a cluster, inter-texture coupling leads to the splitting of these modes into $N$-fold multiplets, where $N$ denotes the number of asymmetric antibimerons. To rationalize these findings, we introduce an effective coupled-oscillator model based on meron pairs that captures the essential collective dynamics of the system. This emergent classical mechanics description reveals that the motion of asymmetric antibimeron clusters can be understood in terms of well-defined normal modes governed by topology-constrained particle-like degrees of freedom. These results establish coupled asymmetric antibimerons as a tunable platform for spin-wave based nano-oscillators, whose normal-mode spectrum is controllable through cluster size, thus providing a programmable set of low-lying resonances for these nano-oscillators.

cond-mat.mes-hall↗

The evolution of electron dispersion in the series of rare-earth tritelluride compounds obtained from their charge-density-wave properties and susceptibility calculations

We calculated electron susceptibility of rare-earth tritelluride compounds RTe$_3$ as a function of temperature, wave vector and electron-dispersion parameters. Comparison of results obtained with the available experimental data on the transition temperature and on the wave vector of a charge-density wave in these compounds allowed us to predict values and the evolution of electron-dispersion parameters with the variation of atomic number of rare-earth element R.

cond-mat.str-el↗