Prof Arzhang Ardavan

Abstract:

We report high-field magnetotransport measurements on β″-(BEDT- TTF)4[(H3O)M(C2O4) 3]· solvent, where M=Ga3+, Cr3+ and Fe3+ and solvent=C5H5N. In spite of their differing transition metal-ions, M, the three compounds exhibit similar magnetic quantum oscillation spectra superimposed on a positive magnetoresistance. At least four independent quantum oscillation frequencies have been identified, corresponding to two different hole and electron pockets of the Fermi surface which follow the rules of a compensated metal. Observation of the small pockets could be the result of the Fermi surface reconstruction induced by a possible density wave. The effective masses are very similar for different samples and for different pockets range between meff ≈ 0.5-1.1 me whereas the Dingle temperatures varies between TD ≈ 1.4-4 K. At low temperature, the longitudinal magnetoresistance violates Kohler's rule, suggesting that the interlayer transport in these quasi-2D systems cannot be related to a single scattering time and that the disorder plays an important role. © EDP Sciences.