https://doi.org/10.1140/epjb/e2003-00136-1
Optical properties of the quasi-two-dimensional dichalcogenides 2H-TaSe2 and 2H-NbSe2
1
Department of Physics, University of California, San
Diego, La Jolla CA 92093, USA
2
Laboratorium für Festkörperphysik, ETH Zürich,
8093 Zürich, Switzerland
3
Institute of Physics of Complex Matter, EPF Lausanne,
1015 Lausanne,
Switzerland
4
Lucent Technologies, Murray Hill, NJ 07974, USA and
Fakultät für Physik, Universität Konstanz, 78457 Konstanz,
Germany
Corresponding author: a degiorgi@solid.phys.ethz.ch
Received:
28
October
2002
Revised:
10
March
2003
Published online:
23
May
2003
We present a comprehensive analysis of the optical constants of
the two-dimensional dichalcogenide materials and
, in an attempt to address the physics of
two-dimensional correlated systems. The title compounds were
studied over several decades in frequency, from the far-infrared
to the ultraviolet. Measurements with linearly polarized light
have allowed us to obtain both the in-plane and out-of-plane
components of the conductivity tensor. Although the
electromagnetic response of dichalcogenides is strongly
anisotropic, both the in-plane and out-of-plane components of the
conductivity tensor share many common features, including the
presence of a well-defined metallic component, as well as a
“mid-infrared band”. We discuss the implications of these results
in the context of the spectroscopic results of other classes of
low-dimensional conductors such as the high-temperature
superconducting cuprates. In
particular, the analysis of the redistribution of the spectral
weight as a function of temperature, as well as the behavior of
the quasiparticles relaxation rate, points to significant
distinctions between the charge dynamics of dichalcogenides and
other classes of low dimensional conductors.
PACS: 78.20.-e – Optical properties of bulk materials and thin films / 71.45.Lr – Charge-density-wave systems / 74.25.Gz – Optical properties
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2003