Ga. Farnan et al., Dielectric function of YBCO in the mid-infrared: temperature and doping dependence at 3.392 mu m, PHYSICA C, 341, 2000, pp. 2273-2274
The ab-plane dielectric function at 3392mm of thin films of YBa2Cu3O7-delta
with a wide range of doping has been measured using attenuated total refle
ctance. while epsilon (2), and therefore sigma (1), are temperature indepen
dent, /epsilon (1)/ decreases by similar to 25% with increasing temperature
. A stronger dependence an doping is observed: the magnitudes of epsilon (1
) and epsilon (2) are both strongly suppressed as delta increases. A genera
lised Drude analysis shows that the plasma frequency is temperature-indepen
dent, but scales with doping. The scattering rate increases with temperatur
e, and also increases with decreasing doping, consistent with stronger coup
ling in the underdoped regime.