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Register a new userRebuttal to Comment by V.M. Krasnov on Counterintuitive consequence of heating in strongly-driven intrinsic junctions of Bi2Sr2CaCu2O8+d Mesas
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In our article [1], we found that with increasing dissipation there is a clear, systematic shift and sharpening of the conductance peak along with the disappearance of the higher-bias dip/hump features (DHF), for a stack of intrinsic Josephson junctions (IJJs) of intercalated Bi2Sr2CaCu2O8+{delta} (Bi2212). Our work agrees with Zhu et al [2] on unintercalated, pristine Bi2212, as both studies show the same systematic changes with dissipation. The broader peaks found with reduced dissipation [1,2] are consistent with broad peaks in the density-of-states (DOS) found among scanning tunneling spectroscopy [3] (STS), mechanical contact tunneling [4] (MCT) and inferred from angle (momentum) resolved photoemission spectroscopy [5] (ARPES); results that could not be ignored. Thus, sharp peaks are extrinsic and cannot correspond to the superconducting DOS. We suggested that the commonality of the sharp peaks in our conductance data, which is demonstrably shown to be heating-dominated, and the peaks of previous intrinsic tunneling spectroscopy (ITS) data implies that these ITS reports might need reinterpretation.
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Anomalously high and sharp peaks in the conductance of intrinsic Josephson junctions in Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+delta}$ (Bi2212) mesas have been universally interpreted as superconducting energy gaps, but here we show they are a result of heating. This interpretation follows from a direct comparison to the equilibrium gap, $mathit Delta$, measured in break junctions on similar Bi2212 crystals. As the dissipated power increases with a greater number of junctions in the mesa, the conductance peak abruptly sharpens and its voltage decreases to well below 2$mathit Delta$. This sharpening, found in our experimental data, defies conventional intuition of heating effects on tunneling spectra, but it can be understood as an instability into a nonequilibrium two-phase coexistent state. The measured peak positions occur accurately within the voltage range that an S-shaped backbending is found in the {it calculated} current-voltage curves for spatially {it uniform} self-heating and that S-shape implies the potential for the uniform state to be unstable.
We have studied experimentally and numerically temperature profiles and the formation of hot spots in intrinsic Josephson junction stacks in Bi2Sr2CaCu2O8 (BSCCO). The superconducting stacks are biased in a state where all junctions are resistive. The formation of hot spots in this system is shown to arise mainly from the strongly negative temperature coefficient of the c-axis resistivity of BSCCO at low temperatures. This leads to situations where the maximum temperature in the hot spot can be below or above the superconducting transition temperature Tc. The numerical simulations are in good agreement with the experimental observations.
We have determined the electron-coupling spectrum of superconducting Bi2Sr2CaCu2O8+d from high-resolution angle-resolved photoemission spectra by two deconvolution-free robust methods. As hole concentration decreases, the coupling spectral weight at low energies ~<15 meV shows a twofold and nearly band-independent enhancement, while that around ~65 meV increases moderately, and that in ~>130 meV decreases leading to a crossover of dominant coupling excitation between them. Our results suggest the competition among multiple screening effects, and provide important clues to the source of sufficiently strong low-energy coupling, {lambda}LE ~ 1, in underdoped system.
We report Raman measurements on Bi2Sr2CaCu2O8+d single crystals which allow us to quantitavely evaluate the doping dependence of the density of Cooper pairs in the superconducting state. We show that the drastic loss of Cooper pairs in the antinodal region as the doping level is reduced, is concomitant with a deep alteration of the quasiparticles dynamic above Tc and consistent with a pseudogap which competes with superconductivity. Our data also reveal that the overall density of Cooper pairs evolves with doping, distinctly from the superfluid density above the doping level pc=0.2.
Inclusion of correlation effects affects quantitatively the agreement with experiment as far as the value of energy shift and the level of doping is concerned, and our original statement that nesting at ($pi$,0) can be responsible for magnetic behavior of FeTe is hereby reinstated.
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