Dimensionality-Driven Insulator-to-Metal Transition in the Bechgaard Salts
V. Vescoli,
L. Degiorgi,
W. Henderson,
G. Grüner,
K. P. Starkey,
L. K. Montgomery
Optical experiments were conducted on a series of organic linear
chain conductors with different values of the interchain single-electron transfer integral tb,
which quantifies the degree of anisotropy. Electron-electron
interactions together with Umklapp scattering resulted in a correlation
gap and an insulating state for small tb.
An insulator-to-metal transition was observed when tb exceeded a critical value, on the order
of the correlation gap Egap. The absence of a
plasma edge on the insulator side of the transition for polarization
perpendicular to the chains suggests that the electrons are confined to
the chains. The optical features of the metallic state, when contrasted
with the magnetic properties, are suggestive of spin-charge separation.
V. Vescoli and L. Degiorgi, Laboratorium für
Festkörperphysik, Eidgenössische Technische Hochschule,
CH-8093 Zürich, Switzerland. W. Henderson and G. Grüner,
Department of Physics, University of California, Los Angeles, CA
90095-1547, USA. K. P. Starkey and L. K. Montgomery,
Department of Chemistry, University of Indiana, Bloomington, IN 47405, USA.
