Bimeron nanoconfined design

We report on the stabilization of the topological bimeron excitations in confined geometries. The Monte Carlo simulations for a ferromagnet with a strong Dzyaloshinskii-Moriya interaction revealed the formation of a mixed skyrmion-bimeron phase. The vacancy grid created in the spin lattice drastically changes the picture of the topological excitations and allows one to choose between the formation of a pure bimeron and skyrmion lattice. We found that the rhombic plaquette provides a natural environment for stabilization of the bimeron excitations. Such a rhombic geometry can protect the topological state even in the absence of the magnetic field.Comment: 5 pages, 7 figure

Profile approach for recognition of three-dimensional magnetic structures

We propose an approach for low-dimensional visualisation and classification of complex topological magnetic structures formed in magnetic materials. Within the approach one converts a three-dimensional magnetic configuration to a vector containing the only components of the spins that are parallel to the z axis. The next crucial step is to sort the vector elements in ascending or descending order. Having visualized profiles of the sorted spin vectors one can distinguish configurations belonging to different phases even with the same total magnetization. For instance, spin spiral and paramagnetic states with zero total magnetic moment can be easily identified. Being combined with a simplest neural network our profile approach provides a very accurate phase classification for three-dimensional magnets characterized by complex multispiral states even in the critical areas close to phases transitions. By the example of the skyrmionic configurations we show that profile approach can be used to separate the states belonging to the same phase

Supervised learning magnetic skyrmion phases

We propose and apply simple machine learning approaches for recognition and classification of complex non-collinear magnetic structures in two-dimensional materials. The first approach is based on the implementation of the single-hidden-layer neural network that only relies on the z projections of the spins. In this setup one needs a limited set of magnetic configurations to distinguish ferromag- netic, skyrmion and spin spiral phases, as well as their different combinations in transitional areas of the phase diagram. The network trained on the configurations for square-lattice Heisenberg model with Dzyaloshinskii-Moriya interaction can classify the magnetic structures obtained from Monte Carlo calculations for triangular lattice and vice versa. The second approach we apply, a minimum distance method performs a fast and cheap classification in cases when a particular configuration is to be assigned to only one magnetic phase. The methods we propose are also easy to use for analysis of the numerous experimental data collected with spin-polarized scanning tunneling microscopy and Lorentz transmission electron microscopy experiments.Comment: 9 pages, 14 figures. Accepted for publication in Physical Review

Quantifying spatio-temporal patterns in classical and quantum systems out of equilibrium

A rich variety of non-equilibrium dynamical phenomena and processes unambiguously calls for the development of general numerical techniques to probe and estimate a complex interplay between spatial and temporal degrees of freedom in many-body systems of completely different nature. In this work we provide a solution to this problem by adopting a structural complexity measure to quantify spatio-temporal patterns in the time-dependent digital representation of a system. On the basis of very limited amount of data our approach allows to distinguish different dynamical regimes and define critical parameters in both classical and quantum systems. By the example of the discrete time crystal realized in non-equilibrium quantum systems we provide a complete low-level characterization of this nontrivial dynamical phase with only processing bitstrings, which can be considered as a valuable alternative to previous studies based on the calculations of qubit correlation functions.Comment: Monitoring a quantum evolution has been adde

EVOLUTION OF THE MAGNETIC PROPERTIES OF TWO-DIMENSIONAL Fe3GeTe2 UNDER STRAIN

In this work we study the evolution of magnetic properties, magnetization, and magnon spectra of Fe3GeTe2 changes under in-plane biaxial strain. We found that moderate tensile strain significantly increases Curie temperature, while compressive one destroys FM order.This work was supported by the Russian Science Foundation Grant 21-72-10136

Glass-based charged particle detector performance for Horizon-T EAS detector system

An implementation of a novel of glass-based detector with fast response and wide detection range is needed to increase resolution for ultra-high energy cosmic rays detection. Such detector has been designed and built for the Horizon-T detector system at Tien Shan high-altitude Science Station. The main characteristics, such as design, duration of the detector pulse and calibration of a single particle response are discussed.Comment: Simulation is used to assess glass detector performance. Simulation is validated first when compared to scintillator detector experimental measurements. Final results summarized in table. Updated May 2017 with calibrations updat

Horizon-T Experiment Detailed Calibration of Cables

The ability to extract the pulse width and translate it into the actual disk width of the Extensive Air Showers (EAS) is a hard one requiring accurate knowledge of the system performance. For that, the analysis for the cable calibration for Horizon-10T detectors has been re-analyzed in a different form that allows for better signal width measurements. An innovative detector system Horizon-10T, constructed to study EAS in the energy range above 1016 eV coming from a wide range of zenith angles (0o - 85o), is located at Tien Shan high-altitude Science Station of Lebedev Physical Institute of the Russian Academy of Sciences at approximately 3340 meters above the sea level.Comment: in-depth analysis of cable calibration for 'new' cables only v2 corrects minor typo