Analysis of magnetic relaxation in YBa2Cu3O7−δ leading to temperature‐independent activation energies

Within the framework of first‐order kinetics the activation energy spectrum p(U) for thermal activated flux motion in YBa2Cu3O7−δ single crystals is derived from the time decay of the magnetic polarization μ0M(t). The distribution function p(U) turns out to be temperature independent, so that the time dependence of μ0M(t,T) can be described by one unique spectrum p(U) in the whole temperature range 0 < T < Tc. Concerning the crystal directions H∥c and H⊥c, respectively, a threshold energy in the case H⊥c is noticed which may be related to the Peierls potential, formed by the Cu‐O planes.