11 research outputs found
Correlation gap in the optical spectra of the two-dimensional organic metal (BEDT-TTF)_4[Ni(dto)_2]
Optical reflection measurements within the highly conducting (a,b)-plane of
the organic metal (BEDT-TTF)_4[Ni(dto)_2] reveal the gradual development of a
sharp feature at around 200 cm as the temperature is reduced below 150 K. Below
this frequency a narrow Drude-like response is observed which accounts for the
metallic behavior. Since de Haas-von Alphen oscillations at low temperatures
confirm band structure calculations of bands crossing the Fermi energy, we
assign the observed behavior to a two-dimensional metallic state in the
proximity of a correlation induced metal-insulator transition.Comment: 4 pages, 2 figure
Investigations of the Fermi surface of a new organic metal: (BEDT-TTF)
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