Comment on Counterintuitive consequence of heating in strongly-driven intrinsic junctions of Bi2Sr2CaCu2O8+δ mesas

In a recent paper, Kurter et al. [Phys. Rev. B 81, 224518 (2010)] analyzed self-heating in strongly-driven Bi2Sr2CaCu2O8+delta mesa structures. They attributed observed peaks in conductance to heating of mesas up to the superconducting critical temperature T-c, extrapolated this statement to much smaller mesas, used in intrinsic tunneling spectroscopy (ITS), and called for reinterpretation of ITS data. They also suggested a universal figure of merit for the shape of tunneling characteristics. Here, I argue that the peak in c-axis conductance usually occurs well below Tc; that for small ITS mesas, it represents the superconducting gap; and that the genuine shape of tunneling characteristics for cuprates is not universal but depends on doping, uniformity, and geometry.