0000000000414194
AUTHOR
R. Taukulis
Diffusion in active magnetic colloids
Abstract Properties of active colloids of circle swimmers are reviewed. As a particular example of active magnetic colloids the magnetotactic bacteria under the action of a rotating magnetic field is considered. The relation for a diffusion coefficient due to the random switching of the direction of rotation of their rotary motors is derived on the basis of the master equation. The obtained relation is confirmed by the direct numerical simulation of random trajectory of a magnetotactic bacterium under the action of the Poisson type internal noise due to the random switching of rotary motors. The results obtained are in qualitative and quantitative agreement with the available experimental r…
Thermal Expansion, Burns Temperature and Electromechanical Properties in Na1/2Bi1/2TiO3-SrTiO3-PbTiO3Solid Solutions
Thermal expansion and electromechanical properties are studied for compositions Na1/2Bi1/2TiO3-SrTiO3-PbTiO3, belonging to various locations in the phase diagram. The main purpose of the studies is to extend the range of physical properties, which characterise the relaxor state and could be used for comparison with other relaxors. Possibility to evaluate Burns temperature from thermal expansion is discussed. The obtained results are compared to the well-know relaxor ferroelectric PLZT.
Coupled stochastic dynamics of magnetic moment and anisotropy axis of a magnetic nanoparticle
An algorithm is developed for numerical simulation of coupled stochastic dynamics of magnetic moment and magnetic anisotropy axis of a nanoparticle. Time-correlation functions of the magnetic moment and its components longitudinal and transverse to the magnetic anisotropy axis are calculated by averaging along the stochastic trajectory. The longitudinal and transverse relaxation times are found by fitting the time correlation functions. Existing theoretical relations derived by the effective field approach in the limit of small fields are confirmed. The time-correlation functions of magnetic moments of nanoparticles in dependence on their properties are calculated numerically for arbitrary …