A new dissipation behavior is reported in superconducting ${\mathrm{Bi}}_{2.2}{\mathrm{Sr}}_2{\mathrm{Ca}}_{0.8}{\mathrm{Cu}}_2{\mathrm{O}}_{8+\delta }$ for all temperatures below $T_c$ and all magnetic fields exceeding $H_{c1\mathrm{}}$. The current-independent electrical resistivity is thermally activated and can be described by an Arrhenius law with a single prefactor and a magnetic-field- and orientation-dependent activation energy $U_0(H,\phi )$. This behavior is markedly different from past observations and will be discussed in terms of flux creep and flux flow. This thermally activated behavior implies a finite resistance at all temperatures and all fields exceeding $H_{c1\mathrm{}}$ determined by the activation energy as the only parameter.

• Received 27 July 1988

DOI:https://doi.org/10.1103/PhysRevLett.61.1662