Shubnikov–de Haas Effect and Angular-dependent Magnetoresistance in New Layered Organic Conductors ET₃Cl(DFBIB) and ET₃Br(pBIB)

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This paper reports the measurements of Shubnikov–de Haas (SdH) and angular-dependent magnetoresistance oscillations (AMROs) for new layered organic conductors ET₃Cl(DFBIB) and ET₃Br(pBIB), where ET, DFBIB, and pBIB stand for bis(ethylenedithio)tetrathiafulvalene, 1,4-difluoro-2,5-bis(iodoethynyl)benzene, and p-bis(iodoethynl)benzene, respectively. Each of them has only a two-dimensional Fermi surface (FS), whose cross sectional area corresponds to about 50% of the first Brillouin zone. No significant difference between them is found in the size and shape of the cross-section of the FS. In spite of the similarity of the electronic state, the sharp peaks in the magnetoresistance are clearly observed for ET₃Cl(DFBIB) under in-plane magnetic fields, while anomalous broad peaks for ET₃Br(pBIB). The results suggest that the anion structure play an important role in the interlayer transport.