Current-temperature diagram of resistive states in long superconducting YBa ₂Cu ₃O ₇ strips

Using a sequence of stepped bias currents in the nanosecond range, we have studied the destruction of superconductivity in c-axis textured YBa ₂Cu ₃O ₇ strips of various thickness and structure (single or multi-layers). Sufficiently far from T _c, vortex flow fades out and gradually gives way to localized dissipative structures, which can be interpreted either as Phase-Slip Centers (PSC) or normal Hot Spots (HS). A plot of the corresponding threshold currents in the current - temperature (I - T) plane indicates when each of them will occur, and how to switch over from one to the other, in a manner similar to that demonstrated for metallic materials (cf. Ladan et al., J. Low Temp. Phys. 153:103, 2008). The capability of some YBCO strips to support PSC's at arbitrarily low temperatures escapes the common picture.