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MOSCOW, April 1. /TASS /. Scientists from the Moscow Institute of Physics and Technology (MIPT) and Prokhorov General Physics Institute have found that microscopic magnetic vortices (called skyrmions) in manganese monosilicide (MnSi) are able to create a single structure, or they can also split up individually. Studying the behavior of skyrmions will help to create unique quantum devices based on new physical principles, the MIPT press-service said.
"Electronics which is based on the use of individual skyrmions, will open up new prospects for miniaturizing devices and will reduce control currents", MIPT said.
Manganese monosilicide is a model object for spintronics - a branch of quantum electronics to study the possibility of controlling spin-polarized currents (conventional radio and electronic devices use non-polarized charge carriers). Spintronics-based devices, which use stable magnetic states as information bits, will help scientists to develop faster and more compact processors with low levels of power consumption, and fast and reliable non-volatile memory. This is why scientists are carefully studying the electronic and magnetic properties of materials with exotic magnetic structures.
Theorists are not yet able to fully explain the unusual magnetic properties of manganese monosilicide. For example, at very low temperatures (approximately -245C) the external magnetic field inside a manganese monosilicide crystal "rotates" the electron spins into a complex arrangement of tiny magnetic vortices, or skyrmions. The structure formed by the vortices resembles a honeycomb, with cells that are approximately 18 nanometres wide. In order to use a skyrmion for practical purposes, scientists need to know whether the periodic magnetic structure consists of individual skyrmions (see image) that can be examined independently of one another, or forms a more complex magnetic structure which depends on the direction of the crystal and cannot be divided into separate vortices.
In a study published in Scientific Reports Russian scientists from MIPT and GPI RAS succeeded in measuring the resistivity of solid manganese monosilicide to a very high degree of accuracy depending on the temperature and direction of the magnetic field. These data helps scientist to make a conclusion about the MnSi magnetic structure.
"Our experiment has revealed a clear distinction between the different states of the skyrmion phase," said one of the authors, Prof. Sergey Demishev. "MnSi has two types of skyrmion lattices with a different physical nature. First area corresponds to the skyrmion lattice formed as a result of the condensation of individual magnetic vortices and other one is a complex anisotropic magnetic phase which is not able to break down into individual quasi-particles - skyrmions. Observations of a skyrmion lattice consisting of individual vortices confirm the profound analogy with type II superconductors, the mixed state of which is formed by Abrikosov-type vortices".
From a practical point of view, individual skyrmions can be used to transmit and store information and perform various logical operations. The only thing that physicists need to do now is to find materials similar to high-temperature superconductors, in which tiny magnetic vortices will be stable at room temperatures.
Fig. Types of magnetic structure of manganese monosilicide MnSi depending on magnetic field strength, temperature and crystal orientationImage courtesy of the authors of the study