Berezinskii-Kosterlitz-Thouless Paired Phase in Coupled XY Models.

We study the effect of a linear tunneling coupling between two-dimensional systems, each separately exhibiting the topological Berezinskii-Kosterlitz-Thouless (BKT) transition. In the uncoupled limit, there are two phases: one where the one-body correlation functions are algebraically decaying and the other with exponential decay. When the linear coupling is turned on, a third BKT-paired phase emerges, in which one-body correlations are exponentially decaying, while two-body correlation functions exhibit power-law decay.

Improved efficiency of heat generation in nonlinear dynamics of magnetic nanoparticles.

The deterministic Landau-Lifshitz-Gilbert equation has been used to investigate the nonlinear dynamics of magnetization and the specific loss power in magnetic nanoparticles with uniaxial anisotropy driven by a rotating magnetic field. We propose a new type of applied field, which is "simultaneously rotating and alternating," i.e.

Magnetic particle hyperthermia: power losses under circularly polarized field in anisotropic nanoparticles.

The deterministic Landau-Lifshitz-Gilbert equation has been used to investigate the nonlinear dynamics of magnetization and the specific power loss in magnetic nanoparticles with uniaxial anisotropy driven by a rotating magnetic field, generalizing the results obtained for the isotropic case found by P. F. de Châtel, I.

Functional renormalization group approach to the sine-Gordon model.

The renormalization group flow is presented for the two-dimensional sine-Gordon model within the framework of the functional renormalization group method by including the wave-function renormalization constant. The Kosterlitz-Thouless-Berezinski type phase structure is recovered as the interpolating scaling law between two competing IR attractive area of the global renormalization group flow.

Magnetic particle hyperthermia: Néel relaxation in magnetic nanoparticles under circularly polarized field.

The mechanism of magnetization reversal in single-domain ferromagnetic particles is of interest in many applications, in most of which losses must be minimized. In cancer therapy by hyperthermia the opposite requirement prevails: the specific loss power should be maximized. Of the mechanisms of dissipation, here we study the effect of Néel relaxation on magnetic nanoparticles unable to move or rotate and compare the losses in linearly and circularly polarized fields.