Spin-zero anomaly in the magnetic quantum oscillations of a two-dimensional metal

We report on an anomalous behavior of the spin-splitting zeros in the de Haas-van Alphen (dHvA) signal of a quasi-two-dimensional organic superconductor. The zeros as well as the angular dependence of the amplitude of the second harmonic deviate remarkably from the standard Lifshitz-Kosevich (LK) prediction. In contrast, the angular dependence of the fundamental dHvA amplitude as well as the spin-splitting zeros of the Shubnikov-de Haas signal follow the LK theory. We can explain this behavior by small chemical-potential oscillations and find a very good agreement between theory and experiment. A detailed wave-shape analysis of the dHvA signal corroborates the existence of an oscillating chemical potential

Electromagnetic response of a static vortex line in a type-II superconductor : a microscopic study

The electromagnetic response of a pinned Abrikosov fluxoid is examined in the framework of the Bogoliubov-de Gennes formalism. The matrix elements and the selection rules for both the single photon (emission - absorption) and two photon (Raman scattering) processes are obtained. The results reveal striking asymmetries: light absorption by quasiparticle pair creation or single quasiparticle scattering can occur only if the handedness of the incident radiation is opposite to that of the vortex core states. We show how these effects will lead to nonreciprocal circular birefringence, and also predict structure in the frequency dependence of conductivity and in the differential cross section of the Raman scattering.Comment: 14 pages (RevTex

Prediction of inorganic superconductors with quasi-one-dimensional crystal structure

Models of superconductors having a quasi-one-dimensional crystal structure based on the convoluted into a tube Ginzburg sandwich, which comprises a layered dielectric-metal-dielectric structure, have been suggested. The critical crystal chemistry parameters of the Ginzburg sandwich determining the possibility of the emergence of superconductivity and the Tc value in layered high-Tc cuprates, which could have the same functions in quasi-one-dimensional fragments (sandwich-type tubes), have been examined. The crystal structures of known low-temperature superconductors, in which one can mark out similar quasi-one- dimensional fragments, have been analyzed. Five compounds with quasi-one-dimensional structures, which can be considered as potential parents of new superconductor families, possibly with high transition temperatures, have been suggested. The methods of doping and modification of these compounds are provided.Comment: 22 pages, 14 figures and 2 table

Gender differences in coerced patients with schizophrenia

European Commission (Quality of life and Management of Living Resources Programme, contract number QLG4-CT- 2002-01036), Czech Ministry of Education research grant MSM002160849, and research grants PRVOUK–P26/LF1/4 and PRVOUK–P03/LF1/

The Flux-Line Lattice in Superconductors

Magnetic flux can penetrate a type-II superconductor in form of Abrikosov vortices. These tend to arrange in a triangular flux-line lattice (FLL) which is more or less perturbed by material inhomogeneities that pin the flux lines, and in high-$T_c$ supercon- ductors (HTSC's) also by thermal fluctuations. Many properties of the FLL are well described by the phenomenological Ginzburg-Landau theory or by the electromagnetic London theory, which treats the vortex core as a singularity. In Nb alloys and HTSC's the FLL is very soft mainly because of the large magnetic penetration depth: The shear modulus of the FLL is thus small and the tilt modulus is dispersive and becomes very small for short distortion wavelength. This softness of the FLL is enhanced further by the pronounced anisotropy and layered structure of HTSC's, which strongly increases the penetration depth for currents along the c-axis of these uniaxial crystals and may even cause a decoupling of two-dimensional vortex lattices in the Cu-O layers. Thermal fluctuations and softening may melt the FLL and cause thermally activated depinning of the flux lines or of the 2D pancake vortices in the layers. Various phase transitions are predicted for the FLL in layered HTSC's. The linear and nonlinear magnetic response of HTSC's gives rise to interesting effects which strongly depend on the geometry of the experiment.Comment: Review paper for Rep.Prog.Phys., 124 narrow pages. The 30 figures do not exist as postscript file