Scaling of the microwave magneto-impedance in Tl 2Ba 2CaCu 2O 8+ δ thin films

Abstract

We present measurements of the magnetic field-induced microwave complex resistivity changes at 47 GHz in Tl 2Ba 2CaCu 2O 8+ δ (TBCCO) thin films, in the ranges 58 K < T < T c and 0 < μ 0 H < 0.8 T. The large imaginary part Δ ρ 2( H) points to strong elastic response, but the data are not easily reconciled with a rigid vortex model. We find that, over a wide range of temperatures, all the pairs of curves Δ ρ 1( H) and Δ ρ 2( H) can be collapsed on a pair of scaling curves Δ ρ 1[ H/ H ∗( T)], Δ ρ 2[ H/ H ∗( T)], with the same scaling field H ∗( T). We argue that H ∗( T) is related to the loss of vortex rigidity due to a vortex transformation.