Investigations of the Fermi surface of a new organic metal: (BEDT-TTF)₄[ Ni(dto)

¹ 3. Physichalisches Institut, Universität Stuttgart Pfaffenwaldring 57, 70550 Stuttgart, Germany
² High Magnetic Field Laboratory MPI-FKF and CNRS, BP 166, F-38042 Grenoble Cedex 9, France
³ Department of Chemistry, North Carolina State University Raleigh, North Carolina 27695, USA
⁴ Anorganisch-Chemisches Institut, Universität Heidelberg Im Neuenheimer Feld 270, 69120 Heidelberg, Germany

Received: 2 February 2000
Accepted: 10 May 2000

Abstract

The Fermi surface (FS) of the new organic metal (BEDT-TTF)₄[ Ni(dto) has been investigated by de Haas-van Alphen (dHvA) and Shubnikov-de Haas (SdH) experiments. In both quantum oscillations with two different frequencies = 634 T and = 4245 T are observed. These results confirm the calculated FS, which consists of one-dimensional and two-dimensional parts separated by a small energy gap. It is shown that the temperature and field dependence of the oscillation amplitudes can be well described by standard Lifshitz-Kosevich theory considering the magnetic breakdown by the so-called coupled network model. Beatings of the oscillation amplitudes are observed by field-dependent dHvA and SdH experiments. They can be explained by a slightly warped FS showing that this material represents a quasi–two-dimensional electronic system. The observed beating nodes in the dHvA and SdH signals appear at different magnetic fields. This fact is discussed in terms of additional scattering mechanisms.