Infrared conductivity

Keywords High Tc superconductors, infrared conductivity, spectral weight... 

An evaluation of the gap value at 300 K was also deduced from the optical data in Ref. 32 on the assumption that the peaks in the infrared conductivity a(o>) [30] were rather resonances below, roughly, 1000 cm"1 but antiresonances above. This is then indicative of an energy gap EG = 2A 1000 cm"1 at 300 K, or 2A 120 meV, a crude value that is not... 

Figure 29 Far-infrared conductivity of (TMTSF)2C104, relaxed phase. The dashed line is the Drude law with 1/r 3.5 cm-1 and

Figure 4.8-17 Infrared conductivity a of TEA(TCNQ)2, experimentally determined (a), and calculated (b), according to Rice et al., 1977, and IR reflectance of (BEDT-TTF)2[Cu(SCN)2J at different temperatures (c), according to Ugawa et al., 1988. The numbers in (a) and (b) refer to structures corresponding to 9 of the 10 Ag modes of TCNQ. A is the single particle electronic transition. The zeros of reflectance in (c) correspond to the four consecutive spectra.

Fig. 4 The photoinduced infrared conductivity solid line) in the insulator precursor of LSCO. The dotted line indicates a simulation based on the small polaron transport theory [4]...

Fig. 3. Experimental (full line) and calculated (dashed line) infrared conductivity and reflectance spectra of (TMTSF)2PF5 at room temperature. Calculated spectra shown in panels (a) and (c) refer to the larger U case, whereas those of panels (b) and (d) refer to the U =0 case.

Figure 2. Infrared conductivity of (2.5-DM-DCNQD2M compounds obtained by Kreuners-Kronig analysis of reflectance spectra. 

While it is difficult to extend infrared measurements below 30-40 cm, microwave experiments (Bonn et al. 1993) performed on crystals from the same source clearly show the existence of a narrow quasiparticle mode with width 1/t 1-3 cm" at low temperatures. This is consistent with the vanishing of 1/t(o —> 0) obtained from the one-component analysis of the infrared conductivity (fig. 8). The width and the spectral weight of the narrow mode in 0 (a>) are strongly temperature dependent. The competition between the suppression of the scattering rate in the superconducting state and the reduction of the spectral weight of the normal fluid (due to pair formation) produces a peak in the T-dependence of (Ti(q)) at T 30-40 K (see inset of fig. 13). 

Figure 5.15 Transient far-infrared conductivity spectra in bare and dye-sensitized ZnO and Ti02 nanoparticles. Symbols (left axis) measured data lines (right axis) calculated mobility of directly photogenerated electrons (solid) and injected electrons (dashed). These lines overlap in the left graph.

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