Analytical treatment of the dHvA frequency combinations due to chemical potential oscillations in an idealized two-band Fermi liquid

de Haas-van Alphen oscillation spectrum is studied for an idealized two-dimensional Fermi liquid with two parabolic bands in the case of canonical (fixed number of quasiparticles) and grand canonical (fixed chemical potential) ensembles. As already reported in the literature, oscillations of the chemical potential in magnetic field yield frequency combinations that are forbidden in the framework of the semiclassical theory. Exact analytical calculation of the Fourier components is derived at zero temperature and an asymptotic expansion is given for the high temperature and low magnetic field range. A good agreement is obtained between analytical formulae and numerical computations.Comment: 10 pages, 4 figure

De Haas-van Alphen Oscillations in the Quasi-Two-Dimensional Organic Conductor κ-(ET)2Cu(NCS)2: The Magnetic Breakdown Approach

We present both experimental data and an analytic theory for the de Haas–van Alphen ~dHvA! effect in the two-dimensional organic single-crystal conductor k -(ET)2Cu(NCS)2. We show that the magnetization oscillation pattern and the fast Fourier transform (FFT) spectrum of our measurements are well described theoretically within the coherent magnetic breakdown (MB) model for a two-dimensional Fermi surface consisting of two open sheets and closed pockets connected by magnetic breakdown centers. The spectrum of Landau quantized energy levels changes substantially due to the MB. Landau bands develop whose bandwidth and relative distance between them oscillate in inverse magnetic field. These oscillations explain the observed fine structure of the magnetization pattern at fields above the MB field with the occurrence of ‘‘forbidden’’ frequencies in the FFT spectrum

Magnetic field - temperature phase diagram of the organic conductor alpha-(BEDT-TTF)2KHg(SCN)4

We present systematic magnetic torque studies of the ``magnetic field - temperature'' phase diagram of the layered organic conductor alpha-(BEDT-TTF)2KHg(SCN)4 at fields nearly perpendicular and nearly parallel to the highly conducting plane. The shape of the phase diagram is compared to that predicted for a charge-density-wave system in a broad field range.Comment: 3 RevTEX pages, 3 PS figures, to be published in JETP Let

Diversité génétique du virus de l' immunodéficience humaine de type-1(VIH-1) in vivo (contribution des espèces virales minoritaires et de la recombination)

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Magnetic Field Dependent Effective Mass in the Organic Superconductor κ-(BEDT-TTF)2\text{}_{2}I3\text{}_{3}

κ-(BEDT-TTF)$\text{}_{2}$I$\text{}_{3}$ is an electronically extreme two-dimensional organic metal with a superconducting transition at around 4 K. In magnetic fields above 12 T the effective mass, as obtained from the temperature dependence of the amplitudes of Shubnikov-de Haas oscillations, is magnetic field dependent as long as the magnetic field is arranged perpendicular to the conducting planes. In contrast to this, by turning the magnetic field by 27° or even only 9° the observed effective mass (as obtained from Shubnikov-de Haas and de Haas-van Alphen measurements) is field independent. We suppose that the occurrence of anyons at temperatures below 1 K in fields above 12 T is the reason for the observed field dependence of the effective mass

de Haas-van Alphen oscillations in the quasi-two-dimensional organic conductor κ-(ET)2Cu(NCS)2: The magnetic breakdown approach

We present both experimental data and an analytic theory for the de Haas-van Alphen (dHvA) effect in the two-dimensional organic single-crystal conductor kappa-(ET)(2)Cu(NCS)(2). We show that the magnetization oscillation pattern and the fast Fourier transform (FFT) spectrum of our measurements are well described theoretically within the coherent magnetic breakdown (MB) model for a two-dimensional Fermi surface consisting of two open sheets and closed pockets connected by magnetic breakdown centers. The spectrum of Landau quantized energy levels changes substantially due to the MB. Landau bands develop whose bandwidth and relative distance between them oscillate in inverse magnetic field. These oscillations explain the observed fine structure of the magnetization pattern at fields above the MB field with the occurrence of "forbidden" frequencies in the FFT spectrum

Investigations of Fermi Surfaces and Effective Masses of the Organic Superconductors (BEDO-TTF)2\text{}_{2}ReO4\text{}_{4}(H2\text{}_{2}O) and κ-(BEDT-TTF)2\text{}_{2}I3\text{}_{3} by Shubnikov-de Haas and de Haas-van Alphen Measurements

The Fermi surfaces and effective masses of (BEDO-TTF)$\text{}_{2}$ReO$\text{}_{4}$(H$\text{}_{2}$0) and κ-(BEDT-TTF)$\text{}_{2}$I$\text{}_{3}$ were investigated by Shubnikov–de Haas (SdH) and de Haas–van Alphen (dHvA) measurements in magnetic fields up to 27 T in the temperature range from 0.5 K to 4.2 K. Two small closed pockets (0.7% and 1.5% of the first Brillouin zone) are observed in (BEDO-TTF)$\text{}_{2}$ReO$\text{}_{4}$(H$\text{}_{2}$0) corresponding very well with two cross-sectional areas of the Fermi surfaces obtained for a hole and an electron pocket from tight binding calculations. In contrast, in κ-(BEDT-TTF)$\text{}_{2}$I$\text{}_{3}$ two relatively large closed sections (13% and 85% of the first Brillouin zone) of the Fermi surfaces are observed, again confirming the tight binding calculations. For κ-(BEDT-TTF)$\text{}_{2}$I$\text{}_{3}$ in magnetic fields above 12 T the effective mass for the larger orbit, as obtained from the temperature dependence of the SdH-oscillation amplitudes, is magnetic field dependent as long as the field is arranged perpendicular to the conducting planes (Θ = 0°). In contrast, from dHvA measurements - which were performed by turning the magnetic field by 27° with respect to the SdH experiments - the observed effective mass is field independent. We suppose that the occurrence of anyons at temperatures below 1 K and in fields above 12 T might be the reason for the observed field dependence of the effective mass in the SdH investigations under the special angle 0°