PACS. 78.20.-e Optical properties of bulk materials and thin films – 71.45.Lr Charge-density-wave systems – 74.25.Gz Optical properties
Springer Online Journal Archives 1860-2000
Abstract: We present a comprehensive analysis of the optical constants of the two-dimensional dichalcogenide materials 2 H - TaSe 2 and 2 H - NbSe 2 , 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.
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