arXiv subjects

Enric Canadell

Publications and source records attributed to Enric Canadell.

23 records · Page 2Linked to original sources

arXiv2007

Crystal structure, Fermi surface calculations and Shubnikov-de Haas oscillations spectrum of the organic metal $θ$-(BETS)$_4$HgBr$_4$(C$_6$H$_5$Cl) at low temperature

The organic metal θ$-(BETS)$_4$HgBr$_4$(C$_6$H$_5$Cl) is known to undergo a phase transition as the temperature is lowered down to about 240 K. X-ray data obtained at 200 K indicate a corresponding modification of the crystal structure, the symmetry of which is lowered from quadratic to monoclinic. In addition, two different types of cation layers are observed in the unit cell. The Fermi surface (FS), which can be regarded as a network of compensated electron and hole orbits according to band structure calculations at room temperature, turns to a set of two alternating linear chains of orbits at low temperature. The field and temperature dependence of the Shubnikov-de Haas oscillations spectrum have been studied up to 54 T. Eight frequencies are observed which, in any case, points to a FS much more complex than predicted by band structure calculations at room temperature, even though some of the observed Fourier components might be ascribed to magnetic breakdown or frequency mixing. The obtained spectrum could result from either an interaction between the FS's linked to each of the two cation layers or to an eventual additional phase transition in the temperature range below 200 K.

cond-mat.str-el↗

arXiv2007

Frequency combinations in the magnetoresistance oscillations spectrum of a linear chain of coupled orbits with a high scattering rate

The oscillatory magnetoresistance spectrum of the organic metal (BEDO)$_5$Ni(CN)$_4\cdot$3C$_2$H$_4$(OH)$_2$ has been studied up to 50 T, in the temperature range from 1.5 K to 4.2 K. In high magnetic field, its Fermi surface corresponds to a linear chain of quasi-two-dimensional orbits coupled by magnetic breakdown (MB). The scattering rate consistently deduced from the data relevant to the basic $α$ and the MB-induced $β$ orbits is very large which points to a significant reduction of the chemical potential oscillation. Despite of this feature, the oscillations spectrum exhibits many frequency combinations. Their effective masses and (or) Dingle temperature are not in agreement with either the predictions of the quantum interference model or the semiclassical model of Falicov and Stachowiak.

cond-mat.str-el↗

arXiv2006

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.

cond-mat.str-el↗

arXiv2006

Pressure dependence of the Shubnikov-de Haas oscillation pectrum of beta''-(BEDT-TTF)4(NH4)[Cr(C2O4)3].DMF

The Shubnikov-de Haas (SdH) oscillation spectra of the beta''-(BEDT-TTF)4(NH4)[Cr(C2O4)\_3].DMF organic metal have been studied in pulsed magnetic fields of up to either 36 T at ambient pressure or 50 T under hydrostatic pressures of up to 1 GPa. The ambient pressure SdH oscillation spectra can be accounted for by up to six fundamental frequencies which points to a rather complex Fermi surface (FS). A noticeable pressure-induced modification of the FS topology is evidenced since the number of frequencies observed in the spectra progressively decreases as the pressure increases. Above 0.8 GPa, only three compensated orbits are observed, as it is the case for several other isostructural salts of the same family at ambient pressure. Contrary to other organic metals, of which the FS can be regarded as a network of orbits, no frequency combinations are observed for the studied salt, likely due to high magnetic breakdown gap values or (and) high disorder level evidenced by Dingle temperatures as large as about 7 K.

cond-mat.str-el↗

arXiv2004

Electronic band structure of alfa-(Per)2M(mnt)2 compounds

The band structure of alfa-(Per)2M(mnt)2, leads to a description of these materials as nearly perfectly one dimensional conductors. The conduction is mainly along the stacking direction of the partially oxidized perylene molecules, (Per)1/2+, with virtually no interchain bandwidth. However, recent high magnetic field experiments suggest orbital coupling of the magnetic field to the electronic structure, indicating a finite interchain bandwidth. The details of the band structure and the possible variances, at low energies, from a perfect one dimensional system are examined. In particular, multiple quasi-one dimensional Fermi surface sheets, which would become important at low temperatures, may lead to an explanation for the experimental finding of a magnetic field induced high field charge density wave ground state. Experimental tests to observe the effects of the finite interchain bandwidth are proposed.

cond-mat.str-el↗