Tatyana G. Prokhorova

Magnetoresistance oscillations up to 32 K in the organic metal β″-(ET)4(H3O)[Fe(C2O4)3] · C6H4Cl2

The magnetic torque and magnetoresistance of the quasi-two-dimensional charge transfer salt β″-(ET)4(H3O)[Fe(C2O4)3] · C6H4Cl2 have been investigated in pulsed magnetic fields of up to 55 T. As opposed to de Haas–van Alphen oscillations, Shubnikov–de Haas oscillations are observed up to temperatures as high as 32 K at ambient pressure despite significant thermal damping in the low-temperature range. This feature, which is also observed under applied pressure, is interpreted in terms of the coexistence of a closed orbit and a quantum interference path with the same cross section.

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.

De Haas-van Alphen oscillations in the compensated organic metal alpha-'pseudo-kappa'-(ET)(4)H3O[Fe(C2O4)(3)]center dot(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 α-‘pseudo-κ’-(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.

De Haas-van Alphen oscillations in the compensated organic metal α-‵pseudo-κ′-(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 α-‘pseudo-κ’-(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.

A new hybrid molecular metal assembling a BEDT-TTF conducting network and the magnetic chain anion [Mn2Cl5(H2O)5]−∞: α-(BEDT-TTF)2[Mn2Cl5(H2O)5]

The synthesis, X-ray crystal and electronic band structures as well as magnetotransport and magnetic properties of the α-(BEDT-TTF)2[Mn2Cl5(H2O)5] radical cation salt with a new type of magnetic polymeric complex anion, [Mn2Cl5(H2O)5]−∞, are reported. The crystal structure is characterized by radical cation layers alternating with layers of the polymeric 1-D chain anions constructed from MnCl3(H2O)3 and MnCl4(H2O)2 octahedra connected to each other via the apical Cl atoms. The calculated electronic band structure suggests that the salt should be a stable 2-D metal and the conductivity measurements show that it exhibits metallic behavior down to 0.4 K. Shubnikov-de Haas oscillations, observed at B > 10 T, are characterized by two fundamental frequencies, corresponding to cross-sections of the Fermi surface, in agreement with the electronic band structure calculations. Magnetic measurements reveal antiferromagnetic correlations in the anion network.