Unconventional superconducting phases in a correlated two-dimensional Fermi gas of nonstandard quasiparticles: a simple model

We discuss a detailed phase diagram and other microscopic characteristics on the applied magnetic field - temperature (H_a-T) plane for a simple model of correlated fluid represented by a two-dimensional (2D) gas of heavy quasiparticles with masses dependent on the spin direction and the effective field generated by the electron correlations. The consecutive transitions between the Bardeen-Cooper-Schrieffer (BCS) and the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phases are either continuous or discontinuous, depending on the values of H_a and T. In the latter case, weak metamagnetic transitions occur at the BCS-FFLO boundary. We single out two different FFLO phases, as well as a reentrant behaviour of one of them at high fields. The results are compared with those for ordinary Landau quasiparticles in order to demonstrate the robustness of the FFLO states against the BCS state for the case with spin-dependent masses (SDM). We believe that the mechanism of FFLO stabilization by SDM is generic: other high-field low-temperature (HFLT) superconducting phases benefit from SDM as well.Comment: 10 pages, 4 figure

A New Species of the Genus Macrargus (Araneae, Linyphiidae, Micronetinae) from the North-East of Ukraine and Redescription of Two Related Species

Macrargus sumyensis Gnelitsa et Koponen, sp. n. is described from the North-East of Ukraine. Two closely related species of the genus Macrargus Dahl, 1886, Macrargus boreus Holm, 1968 and M. multesimus (O.-P. Cambridge, 1875), are redescribed and illustrated in detail.С северо-востока Украины описан Macrargus sumyensis Gnelitsa and Koponen, sp. n. Переописаны и детально проиллюстрированы два близких вида рода Macrargus Dahl, 1886: M. boreus Holm, 1968 и M. multesimus (O.-P. Cambridge, 1875)

Effect of enzyme-aided juice production on the extractability and profile of berry anthocyanins

These experiments showed that the anthocyanin yield increased significantly in certain enzyme-aided treatments as compared to control

Ferromagnetic resonance in ϵ\epsilon-Co magnetic composites

We investigate the electromagnetic properties of assemblies of nanoscale $\epsilon$-cobalt crystals with size range between 5 nm to 35 nm, embedded in a polystyrene (PS) matrix, at microwave (1-12 GHz) frequencies. We investigate the samples by transmission electron microscopy (TEM) imaging, demonstrating that the particles aggregate and form chains and clusters. By using a broadband coaxial-line method, we extract the magnetic permeability in the frequency range from 1 to 12 GHz, and we study the shift of the ferromagnetic resonance with respect to an externally applied magnetic field. We find that the zero-magnetic field ferromagnetic resonant peak shifts towards higher frequencies at finite magnetic fields, and the magnitude of complex permeability is reduced. At fields larger than 2.5 kOe the resonant frequency changes linearly with the applied magnetic field, demonstrating the transition to a state in which the nanoparticles become dynamically decoupled. In this regime, the particles inside clusters can be treated as non-interacting, and the peak position can be predicted from Kittel's ferromagnetic resonance theory for non-interacting uniaxial spherical particles combined with the Landau-Lifshitz-Gilbert (LLG) equation. In contrast, at low magnetic fields this magnetic order breaks down and the resonant frequency in zero magnetic field reaches a saturation value reflecting the interparticle interactions as resulting from aggregation. Our results show that the electromagnetic properties of these composite materials can be tuned by external magnetic fields and by changes in the aggregation structure.Comment: 14 pages, 13 figure

Magnetic phases of one-dimensional lattices with 2 to 4 fermions per site

We study the spectral and magnetic properties of one-dimensional lattices filled with 2 to 4 fermions (with spin 1/2) per lattice site. We use a generalized Hubbard model that takes account all interactions on a lattice site, and solve the many-particle problem by exact diagonalization. We find an intriguing magnetic phase diagram which includes ferromagnetism, spin-one Heisenberg antiferromagnetism, and orbital antiferromagnetism.Comment: 8 pages, 6 figure