Unconventional field and angle dependences of the Shubnikov-de Haas oscillations spectra in the quasi two-dimensional organic superconductor (BEDO-TTF)(2)ReO4H2O

We report on the inter-layer oscillatory conductance of the two-dimensional organic superconductor (BEDO-TTF)(2)ReO4H2O measured in static and pulsed magnetic fields of up to 15 and 52 T, respectively. In agreement with previ ous in-plane studies, two Shubnikov-de Haas oscillation series linked to th e two electron and the hole orbits are observed. The influence of the magni tude and orientation of the magnetic field with respect to the conducting p lane is studied in the framework of the conventional two-and three-dimensio nal Lifshits-Kosevich (LK) model. Deviations of the data from this model ar e observed in low fields strongly tilted with respect to the normal to the conducting plane. In this latter case, the observed behaviour is consistent with an unexplained lowering of the cyclotron effective mass. At high magn etic field. the oscillatory data could have been compatible with the occurr ence of a magnetic breakdown orbit built from the hole and electron orbits. However, the increase of the cyclotron effective mass, linked to the elect ron orbits, as the magnetic field increases above similar to 12 T is consis tent with a field-induced phase transition. In the lower field range, where the conventional LK model holds, the analysis of the angle dependence of t he oscillations amplitude suggests significant renormalisation of tile effe ctive Lande factor.