Evidence for One-Dimensional Metallic Behavior inK2Pt(CN)4

Abstract

from Hall measurements. The calculated frequencies are those for which e =0, while the experimental frequencies are those of the reflectivity minima (e =1). Hence, the experimentally determined frequencies are not exactly the calculated frequencies. Table I has also been plotted as Fig. 3, showing a> + and a>_ as functions of the free-carrier concentration.To give a shift of the surface-plasmon frequency from (x) p to (JO P /J~2, the depletion layer must be approximately a wavelength thick or thicker. If it is much less than a wavelength thick, the surface-plasmon frequency lies between oo p and u) p / /2. This shift of the plasmon frequency with thickness of the dielectric overcoat has been used by Stanford 11 to study the thickness of AgS films on Ag. Note that our etching data indicate that the depletion layer is of order 0.1 mm thick, or approximately one wavelength thick.The cutting of the grating also increases the surface roughness and this presumably plays an important role. This is because the incident photon carries less momentum than a surface plasmon of the same energy. However, we are apparently not observing just a change in surface roughness but also a damage layer, because the reflectance minima shift continuously as etching proceeds.In conclusion we have a very simple model of two coupled harmonic oscillators to explain qualitatively the far-infrared reflectivity of w-type InSb. No attempt was made to include retardation effects or to treat rigorously the plasmonphonon coupling. Clearly, both must be done for a complete treatment. Ngai, Economou, and Cohen 5 have done a calculation (including retarda-We report measurements that give for the first time conclusive evidence for the metallic behavior of a square planar organometallic-complex compound. tion) for a semiconductor bounded by a dielectric for the case where the surface-plasma frequency was high enough (-800 cm" 1 ) so that coupling to the phonons could be neglected. It would be interesting to extend this treatment to include coupling to the phonons. Recently Marschall, Fisher, and Oueisser 12 have observed surface plasmons in InSb using the grating technique. The free carrier concentration was an order of magnitude larger than ours, so that the plasma frequency was well removed from the LO phonon frequency and no coupling effects were observed. In addition, their gratings were ruled with a diamond which did not create a damage layer.Single crystals of K2Pt(CN) 4 Br 0#3 * (H 2 0)" show a Drude-type optical reflectivity for light polarized parallel to the crystal axis. The energy of the plasma edge indicates a metallic density of free carriers. The relatively small conductivity at dc and low frequencies and the photoconductivity at 4.2°K can be understood in terms of a simple model assuming metallic strands interrupted by lattice defects.1060

Irradiation-Induced Confinement in a Quasi-One-Dimensional Metal

“…metallic chain segments between impurity states) and localization on a global scale, over the length of the sample. This picture bears certain similarity to the so-called 'interrupted strand' model (ISM) [21,22], that was applied to explain the activated behavior of the dc conductivity in irradiated quasi-1D organic Peierls insulators [23,24,25]. In the ISM, defects are assumed to be perfectly insulating (in the strictly 1D sense) with no coherent tunneling between the metallic islands.…”

One‐Dimensional Inorganic Complexes

“…These materials become insulators at low temperatures. Photoconductivity in the insulating state has been reported (253). The microwave conductivity (40) of K Z P~( C N )~B~O .~O ( H~O )~ has been reported as being equal to the dc value at room temperature.…”

“…The interrupted strand model was developed for the situation where the blockages dominate the electron motion (253,345,346). The model was originally applied to KzPt(CN)4Bro.3(H20)3 and was also suggested for other systems (434).…”

“…Physical Properties. The physical properties of K Z P~( C N )~X~.~( H Z O )~-(X = C1, Br) have been extensively analyzed in terms of several models for highly conducting one-dimensional systems undergoing a metal-insulator transition including interrupted strands (120,173,253,344,345,346,434) and disorder dominated transport (50,51,336,472). These materials are currently best understood in terms of the physical model of a band conductor undergoing a Peierls transition (433) to a semiconductor as the temperture is lowered (433) with evidence for the presence of a pinned charge density wave (Frohlich collective mode) below 200°K (457).…”

Magnetic and Charge Dynamics in a Doped One-Dimensional Transition Metal Oxide

“…The carriers do not induce clean metallic behavior, which is not surprising for a 1D material where an arbitrarily small concentration of defects leads to localization. YzBaNi05 thus becomes a new member of the very small group [15]of effectively 1 D conductors, and of course the first one whose insulating parent has a spin liquid ground state [6,7].…”