On melting of Boltzmann system of quantum hard spheres.

Melting of a quantum system of hard spheres has been considered in the case when the effects of Bose and Fermi statistics can be neglected. It has been found that the quantum melting line always differs from the classical line except for T = 0, P = 0, where the both lines cross. It is shown that the classical limit is not reachable at any finite temperature.

Modeling longitudinal spin fluctuations in chiral magnets.

We investigate the effect of evolution of energy of longitudinal spin fluctuations on the helimagnetic transition and specific heat in a Heisenberg magnet with the Dzyaloshinskii-Moriya interaction that may arise in a result of applied pressure. Using the classical Monte Carlo calculations for the spin-lattice Hamiltonian accounting for variable spin amplitudes we find that the helical phase transition is pretty robust against the longitudinal spin fluctuations. At the same time the amplitude of the fluctuation hump seen in the specific heat dependence at [Formula: see text] and its position are significantly affected.

Raman studies of nearly half-metallic ferromagnetic CoS2.

We measured the Raman spectra of ferromagnetic, nearly half-metallic, CoS2 over a broad temperature range. All five Raman active modes Ag, Eg, Tg(1), Tg(2) and Tg(3) were observed. The magnetic ordering is indicated by a change of the temperature dependences of the frequency and the line width of Ag and Tg(2) modes at the Curie point.

Global and local superconductivity in boron-doped granular diamond.

Strong granularity-correlated and intragrain modulations of the superconducting order parameter are demonstrated in heavily boron-doped diamond situated not yet in the vicinity of the metal-insulator transition. These modulations at the superconducting state (SC) and at the global normal state (NS) above the resistive superconducting transition, reveal that local Cooper pairing sets in prior to the global phase coherence.

Lost heat capacity and entropy in the helical magnet MnSi.

The heat capacity of MnSi at B = 0 and B = 4 T was measured in the temperature range 2.5-100 K. To analyze the data, calculations of the phonon spectrum and phonon density of states in MnSi were performed.