Anisotropic thermally activated flux flow and flux flow in Bi2Sr2CaCu2Oy crystals

The magnetoresistance of two single crystals of Bi2Sr2CaCu2Oy was investigated in magnetic fields up to 1.6T with a direction angle, θ, between 0° and 180° with respect to the c-axis. The resistivity of the crystals was analyzed in terms of the interpolative expression 1/ϱ=1/ϱFF+1/ϱTAFF, where ϱFF is the flux flow resistivity and ϱTAFF is given by the thermally activated flux flow (TAFF) expression, ϱTAFF=2πϱFF(U/T)exp(-U/T) where T is the …