Thermally Activated Dissipation in Bi sub (2.2) Sr sub 2 Ca sub (0.8) Cu sub 2 O sub (8+delta)

A new dissipation mechanism is reported in superconducting Bi sub 2.2 Sr sub 2 Ca sub 0.8 Cu sub 2 O sub 8+delta for all temperatures below T sub c and all magnetic fields exceeding H sub c1. The resistance is current independent, thermally activated, and can be described by an Arrhenius law with a single prefactor and a magnetic field and orientation dependent activation energy U sub O (H,phi). This behavior involves a new dissipation mechanism since it is markedly different from past observations, including flux creep and flux flow. This thermally activated behavior implies a finite resistance at all temperatures and all fields exceeding H sub c1 determined by the activation energy as the only parameter.