Scaling of the microwave magneto-impedance in Tl2Ba2CaCu2O8+δ thin films

We present measurements of the magnetic field-induced microwave complex resistivity changes at 47 GHz in Tl2Ba2CaCu2O8+δ (TBCCO) thin films, in the ranges 58 K < T < Tc and 0 < μ0H < 0.8 T. The large imaginary part Δρ2(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 Δρ1(H) and Δρ2(H) can be collapsed on a pair of scaling curves Δρ1[H/H*(T)], Δρ2[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