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Phase boundary in the dimensionality of angle-dependent magnetoresistance oscillations in the charge-transfer salt

1996; IOP Publishing; Volume: 8; Issue: 45 Linguagem: Inglês

10.1088/0953-8984/8/45/017

1361-648X

A.A. House, S. J. Blundell, M.M. Honold, John Singleton, J. A. A. J. Perenboom, W. Hayes, Mohamedally Kurmoo, Peter Day,

Quantum and electron transport phenomena

Angle-dependent magnetoresistance oscillations (AMROs) have been studied in the isostructural charge-transfer salts and (where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene) in steady fields of up to 30 T. The shapes of the approximately elliptical quasi-two-dimensional (Q2D) Fermi surfaces that these organic metals possess have been determined at 30 T and are found to be in broad agreement with recent band-structure calculations. The Fermi surface of the salt undergoes a reconstruction at low fields and temperatures, resulting in a change in the dimensionality of the AMROs from Q2D character to quasi-one-dimensional character. This change is associated with the kink transition that is observed in magnetic field sweeps and is attributed to the formation of a spin-density wave ground state. The phase boundary of the change in the AMRO dimensionality has been followed to both the low-temperature high-field (about 23 T) and low-field high-temperature (about 8 K) extremes. The data are compared with recently proposed models of the AMROs and Fermi surfaces for these materials.