Fyzikální ústav Akademie věd ČR

We report on point-contact spectroscopy measurements in PuCoGa5, a moderate heavy-fermion superconductor with a record high critical temperature Tc = 18.5 K. The results prove that the wavefunction of the paired electrons has a d-wave symmetry, with four lobes and nodes, and show that the pairing is likely to be mediated by spin fluctuations. Electronic structure calculations, which take into account the full structure of the f-orbital multiplets of Pu, provide a hint of the possible origin of these fluctuations.

The resistivity of ferromagnetic metals depends strongly on electron scattering by spin disorder caused by finite temperature. We have developed a method for calculation of this part of resistivity from first principles, i.e., without adjustable parameters. Our approach is based on the representation of the system by a set of disordered magnetic moments (the so-called disordered local moment method, DLM).  The full text >>

We analyze how to construct Lyapunov functions describing relaxation to the stationary regime of thermodynamically open systems. These functions are time-monotonous and they can conveniently be applied to the study of stability of stationary states - examples are the free energy in equilibrium respectively the entropy production in weakly non-equilibrium systems. The main result is a proposal of a new Lyapunov function for certain far from equilibrium models, via the dynamical theory of fluctuations.  The full text >>