Resistivity, fluctuation‐enhanced conductivity, and irreversibility line of high‐quality Tl2Ba2Ca2Cu3O10 single crystals

We present measurements of the resistivity tensor components ρ a (T) and ρ c (T) of high-quality Tl 2 Ba 2 Ca 2 Cu 3 O 10 single crystals wit T c = 118... 121 K. The in-plane resistivity ρ a as well as the out-of-plane resistivity ρ c show a metal-like temperature dependence with an anisotropy ratio ρ c /ρ a of up to 10 3 . The coherence length ξ c (0) = O.15 nm could be determined from an analysis of the fluctuation conductivity above T c . From measurements of the ac-susceptibility in magnetic fields up to 10 Tesla the temperature dependence of the depinning line could be obtained. The diffusion coefficient of the flux lines obtained from the frequency dependence of the depinning temperature shows a thermally activated behaviour of the flux motion in the field range 0.1 T ≤ B ≤ 10 T