Overdoped cuprates

Overdoped crystals. In overdoped samples, a threshold structure in the l/r(co) spectra is not observed (fig. 9). In sharp contrast to underdoped materials, the scattering rate shows a temperature dependence over a much broader frequency range, extending at least up to 2000 cm . There are indications that the frequency dependence of /r(co) becomes superlinear in the strongly overdoped cuprates. The overall magnitude of 1/t(co) is reduced compared to underdoped or even optimally doped materials. The effective... 

Some time ago, Uemura et al. (1991) proposed a universal Unear relationship Tc = ps between the superconducting transition temperature and the superfluid density ps of charge carriers for a group of superconducting compounds. Although the Uemura law describes underdoped cuprates well, it does not work for optimal or overdoped cuprates. 

In conclusion, we have shown that according to the doping level in Bi-2212, the onset of superconductivity is associated with a decrease of kinetic energy in the underdoped material, whereas the overdoped material exhibits an increase of kinetic energy. Such a drastic difference confirms that the superconducting state in the underdoped regime of cuprates is unconventional. 

Figure 3 Variation of Tc with hole concentration nh in superconducting cuprate families (adapted from reference 15). Deviations in overdoped region are similar to those in the plots of muon spin relaxation rate against Tc of UemUra et al. (Phvs. Rev. Lett, 1991, 66,...

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