Search academic texts

Information × Registration Number 0212U004377, 0109U001379 , R & D reports Title Forced and spontaneous magnetic dynamics of systems of uniaxial nanoparticles popup.stage_title Head Denisov Stanislav Ivanovich, Registration Date 09-02-2012 Organization Sumy State University popup.description2 The main purpose of the project was the creation of theoretical methods for describing a number of dynamic and fluctuation effects in assembles of ferromagnetic nanoparticles that are induced by pulsed, periodic and random fields. Another purpose was to develop a general theory of systems with one degree of freedom that are under the influence of an arbitrary white noise and have an extremely anomalous behavior. The reorientation (switching) time of the nanoparticle magnetic moment that occurs under the action of pulsed magnetic fields is determined by the numerical solution of the Landau-Lifshitz equation. It is shown that the circularly polarized pulsed magnetic field can reduce the switching time in a few times as compared with the case of linear polarization. The stability theory of the precession states of the magnetic moment with respect the thermal fluctuation is developed using the stochastic Landau-Lifshitz equation and the corresponding Fokker-Planck equation. Within its framework, the method of determination of the lifetime for the periodic and quasiperiodic states of the magnetic moment induced by a circularly polarized magnetic field is developed. It is established analytically and numerically that, if the directions of magnetic field polarization and natural precession are the same, then the frequency dependence of the lifetime has a deep minimum in the vicinity of the Larmor frequency, while in the case of opposite directions this dependence has a pronounced maximum. The methods for the theoretical description of two classes of systems with one degree of freedom are elaborated. The first class includes the strongly excited systems that are described by the Langevin equation with an arbitrary white noise, and the second class contains the systems that are described by the continuous-time random walks whose waiting-time distributions have superheavy tails. Product Description popup.authors Бистрик Юрій Сергійович Денисова Олена Станіславівна Лютий Тарас Володимирович Поляков Олександр Юрійович popup.nrat_date 2020-04-02 Close