Stochastic Dynamics of Magnetosomes in Cytoskeleton

Rotations of microscopic magnetic particles, magnetosomes, embedded into the cytoskeleton and subjected to the influence of an ac magnetic field and thermal noise are considered. Magnetosome dynamics is shown to comply with the conditions of the stochastic resonance under not-too-tight constraints on the character of the particle's fastening. The excursion of regular rotations attains the value of order of radian that facilitates explaining the biological effects of low-frequency weak magnetic fields and geomagnetic fluctuations. Such 1-rad rotations are effectively controlled by slow magnetic field variations of the order of 200 nT.Comment: LaTeX2e, 7 pages with 3 figure

АДСОРБЦИОННАЯ ОЧИСТКА ТРАНСФОРМАТОРНОГО МАСЛА СИЛИКАГЕЛЕМ В СОЧЕТАНИИ КЕРАМИЧЕСКИХ МЕМБРАН

The results of regeneration of exhaust butter are resulted In the article, power transformer from the protracted exploitation. The methods of the adsorption cleaning of transformer butter are considered. Cleaning of transformer butter is experimentally produced from the different types of admixtures with the use of the developed ceramic membranes. The cleared butter rotined high dielectric properties, and fully conformed to the requirements of normative documents.В статье приведены результаты регенерации отработанного масла, силового трансформатора с длительной эксплуатации. Рассмотрены способы адсорбционной очистки трансформаторного масла. Экспериментально произведена очистка трансформаторного масла от различных видов примесей с применением разработанных керамических мембран. Очищенное масло показало высокие диэлектрические свойства, и вполне соответствовало требованиям нормативных документов

Hyperfine interaction and magnetoresistance in organic semiconductors

We explore the possibility that hyperfine interaction causes the recently discovered organic magnetoresistance (OMAR) effect. Our study employs both experiment and theoretical modelling. An excitonic pair mechanism model based on hyperfine interaction, previously suggested by others to explain magnetic field effects in organics, is examined. Whereas this model can explain a few key aspects of the experimental data, we, however, uncover several fundamental contradictions as well. By varying the injection efficiency for minority carriers in the devices, we show experimentally that OMAR is only weakly dependent on the ratio between excitons formed and carriers injected, likely excluding any excitonic effect as the origin of OMAR.Comment: 10 pages, 7 figures, 1 tabl

Single Electron Spin Decoherence by Nuclear Spin Bath: Linked Cluster Expansion Approach

We develop a theoretical model for transverse dynamics of a single electron spin interacting with a nuclear spin bath. The approach allows a simple diagrammatic representation and analytical expressions of different nuclear spin excitation processes contributing to electron spin decoherence and dynamical phase fluctuations. It accounts for nuclear spin dynamics beyond conventional pair correlation models. As an illustration of the theory, we evaluated the coherence dynamics of a P donor electron spin in a Si crystal.Comment: 37 pages, 13 figure

Investigation of high conductivity area at the interface between Ba0.8Sr0.2TiO3 and LaMnO3 after effect of electric field on Ba0.8Sr0.2TiO3 ferroelectric film

The reported study was funded by Russian Scientific Foundation, research project No. 18-12-00260

Effect of magnetic field on high conductivity area at the interface of heterostructure Ba0.8Sr0.2TiO3/LaMnO3

The reported study was funded by Russian Scientific Foundation, research project No. 18-12-00260

High temperature superconductivity at the interface Ba0.8Sr0.2TiO3/La2CuO4

The reported study was funded by Russian Scientific Foundation, research project No. 18-12-00260

Magnetic resonant and non-resonant investigations of LiLnF4 (Ln = Y, Tm) powders

The properties of dielectric powders of the Van Vleck paramagnet LiTmF4 and its diamagnetic analogue LiYF4 have been investigated by both resonant methods (EPR, NMR, and the mass-spectroscopy) and non-resonant ones (conductometry and magnetization measurement). On the basis of experimental data and theoretical calculations a self-consistent model for the magnetic and other properties of these powders is suggested. Two structural phase transitions induced by the magnetic field are discovered in fine LiTmF4 powder at low temperature in a high magnetic field

Comparison of dynamical decoupling protocols for a nitrogen-vacancy center in diamond

We perform a detailed theoretical-experimental study of the dynamical decoupling (DD) of the nitrogen-vacancy (NV) center in diamond. We investigate the DD sequences applied to suppress the dephasing of the electron spin of the NV center induced by the coupling to a spin bath composed of the substitutional nitrogen atoms. The decoupling efficiency of various DD schemes is studied, including both periodic and periodic pulse sequences. For ideal control pulses, we find that the DD protocols with the Carr-Purcell-Meiboom-Gill (CPMG) timing of the pulses provides best performance. We show that, as the number of control pulses increases, the decoupling fidelity scaling differs qualitatively from the predictions of the Magnus expansion, and explain the origin of this difference. In particular, more advanced symmetrized or concatenated protocols do not improve the DD performance. Next, we investigate the impact of the systematic instrumental pulse errors in different periodic and aperiodic pulse sequences. The DD protocols with the single-axis control do not preserve all spin components in the presence of the pulse errors, and the two-axis control is needed. We demonstrate that the two-axis control sequence with the CPMG timing is very robust with respect to the pulse errors. The impact of the pulse errors can be diminished further by symmetrizing this protocol. For all protocols studied here, we present a detailed account of the pulse error parameters which make strongest impact on the DD performance. In conclusion, we give specific recommendations about choosing the decoupling protocol for the system under investigation.Comment: 16 pages, 11 figure