Unconventional magnetic field and pressure dependences of the ground state of the low-dimensional organic superconductor (BEDO-TTF)2ReO4.H2O

¹ Laboratoire de Physique des Solides (ERS CNRS 111), Service National des Champs Magnétiques Pulsés (UMS CNRS 819), INSA, Complexe Scientifique de Rangueil - 31077 Toulouse, France
² Laboratoire de Physique des Solides (URA CNRS 02), Université de Paris-Sud, 91405 Orsay Cédex, France
³ Institute of Chemical Physics in Chernogolovka, Russian Academy of Sciences, Chernogolovka, MD 142432, Russia

Abstract

Magnetotransport experiments have been carried out in the two-dimensional organic metal (BEDO- at temperatures down to 0.4 K and under hydrostatic pressure up to 11 kbar. When measured in magnetic field of a few teslas, the magnetoresistance is large and a steep resistance rise is observed below 4 K, which, as is the case for quasi–one-dimensional TMTSF-based compounds, is the signature of a spin density wave condensation. As already observed at ambient pressure, two series of Shubnikov-de Haas oscillations, linked to hole and electron orbits, are evidenced in the applied pressure range from 3.5 to 11 kbar. Both hole and electron orbit oscillation frequencies (respectively noted F_h and F_e) increase strongly as the pressure increases , while their ratio remains unchanged . As the applied pressure increases, both cyclotron masses either slowly decrease or remain constant, keeping low values when compared to other 2D compounds.