Pressure dependence of the magnetoresistance oscillations spectrum of beta''-(BEDT-TTF)4(NH4)[Fe(C2O4)3].DMF

The pressure dependence of the interlayer magnetoresistance of the quasi-two dimensional organic metal beta''-(BEDT-TTF)4(NH4)[Fe(C2O4)3].DMF has been investigated up to 1 GPa in pulsed magnetic fields up to 55 T. The Shubnikov-de Haas oscillations spectra can be interpreted on the basis of three compensated orbits in all the pressure range studied, suggesting that the Fermi surface topology remains qualitatively the same as the applied pressure varies. In addition, all the observed frequencies, normalized to their value at ambient pressure, exhibit the same sizeable pressure dependence. Despite this behavior, which is at variance with that of numerous charge transfer salts based on the BEDT-TTF molecule, non-monotonous pressure-induced variations of parameters such as the scattering rate linked to the various detected orbits are observed.Comment: accepted for publication in Phys. Rev.

De Haas-van Alphen oscillations in the compensated organic metal alpha-'pseudo-kappa'-(ET)4H3O[Fe(C2O4)3].(C6H4Br2)

Field-, temperature- and angle-dependent Fourier amplitude of de Haas-van Alphen (dHvA) oscillations are calculated for compensated two-dimensional (2D) metals with textbook Fermi surface (FS) composed of one hole and two electron orbits connected by magnetic breakdown. It is demonstrated that, taking into account the opposite sign of electron and hole orbits, a given Fourier component involves combination of several orbits, the contribution of which must be included in the calculations. Such FS is observed in the strongly 2D organic metal alpha-'pseudo-kappa'-(ET)4H3O[Fe(C2O4)3].(C6H4Br2), dHvA oscillations of which have been studied up to 55 T for various directions of the magnetic field with respect to the conducting plane. Calculations are in good quantitative agreement with the data.Comment: European Physical Journal B (2014

Fermi surface and effect of high magnetic fields on the metal-semimetal Peierls-like transition of (TSeT) 2

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Quantum oscillations in coupled orbits networks of (BEDT-TTF) salts with tris(oxalato)metallate anions

Band structure calculations relevant to bis-ethylenedithio-tetrathiafulvalene-based charge transfer salts containing tris(oxalato)metallate anions, with generic formula (BEDT-TTF)4A[M(C2O4)3]·Solv, where A is a monovalent anion, M is a trivalent cation and Solv is a solvent, suggest that their Fermi surface is liable to achieve networks of compensated orbits coupled by magnetic breakdown. Even though this picture accounts for quantum oscillations spectra of a number of these compounds, puzzling results can be noticed in several cases, pointing to the possibility of Fermi surface reconstruction at low temperature.The support of the European Magnetic Field Laboratory (EMFL) is acknowledged. V.N.L. and E.C. acknowledge support of the Spanish MINECO through the Severo Ochoa Centers of Excellence Program under Grant SEV-2015-0496. This work has been supported by MINECO through Grant FIS2015-64886-C5-4-P and Generalitat de Catalunya (2014SGR301). It was also supported by the Russian Foundation for Basic Research, project No 14-03-0019 and the Program No.2 of Presidium of Russian Academy Sciences.Peer reviewe

New insights on frequency combinations and 'forbidden frequencies' in de Haas-van Alphen spectrum of κ-(ET) 2 Cu(SCN) 2

Accepted in Journal of Physics: Condensed Matter (2016)De Haas-van Alphen oscillations of the organic metal κ-(ET) 2 Cu(SCN) 2 have been measured up to 55 T at liquid helium temperatures. The Fermi surface of this charge transfer salt is a textbook example of linear chain of orbits coupled by magnetic breakdown. Accordingly, the oscillation spectrum is composed of linear combinations of the frequencies linked to the α and magnetic breakdown-induced β orbits. The field and temperature dependence of all the observed Fourier components, in particular the 'forbidden frequency' β − α which cannot correspond to a classical orbit, are quantitatively accounted for by analytical calculations based on a second order development of the free energy, i.e. beyond the first order Lifshitz-Kosevich formula

New insights on frequency combinations and forbidden frequencies in the de Haas-van Alphen spectrumof k-(ET)2 Cu(SCN)2

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New insights on frequency combinations and 'forbidden frequencies' in de Haas-van Alphen spectrum of κ-(ET) 2 Cu(SCN) 2

Accepted in Journal of Physics: Condensed Matter (2016)De Haas-van Alphen oscillations of the organic metal κ-(ET) 2 Cu(SCN) 2 have been measured up to 55 T at liquid helium temperatures. The Fermi surface of this charge transfer salt is a textbook example of linear chain of orbits coupled by magnetic breakdown. Accordingly, the oscillation spectrum is composed of linear combinations of the frequencies linked to the α and magnetic breakdown-induced β orbits. The field and temperature dependence of all the observed Fourier components, in particular the 'forbidden frequency' β − α which cannot correspond to a classical orbit, are quantitatively accounted for by analytical calculations based on a second order development of the free energy, i.e. beyond the first order Lifshitz-Kosevich formula

New insights on frequency combinations and 'forbidden frequencies' in de Haas-van Alphen spectrum of κ-(ET) 2 Cu(SCN) 2

Accepted in Journal of Physics: Condensed Matter (2016)De Haas-van Alphen oscillations of the organic metal κ-(ET) 2 Cu(SCN) 2 have been measured up to 55 T at liquid helium temperatures. The Fermi surface of this charge transfer salt is a textbook example of linear chain of orbits coupled by magnetic breakdown. Accordingly, the oscillation spectrum is composed of linear combinations of the frequencies linked to the α and magnetic breakdown-induced β orbits. The field and temperature dependence of all the observed Fourier components, in particular the 'forbidden frequency' β − α which cannot correspond to a classical orbit, are quantitatively accounted for by analytical calculations based on a second order development of the free energy, i.e. beyond the first order Lifshitz-Kosevich formula

Quantum oscillations in coupled orbits networks of (BEDT-TTF) salts with tris(oxalato) metallate anions

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