Pseudogap behavior revealed in interlayer tunneling in overdopedBi2Sr2CaCu2O8+x

Abstract

We report on heating-compensated interlayer tunneling spectroscopy ͑ITS͒ performed on stacks of overdoped Bi 2 Sr 2 CaCu 2 O 8+x intrinsic junctions, where most of the bias-induced heating in the ITS was eliminated. The onset temperature of a pseudogap ͑PG͒, which was revealed in the hump structure of the electronic excitation spectra, nearly reached room temperature for our overdoped intrinsic junctions, which represented the genuine PG onset. At a temperature below but close to T c , both the superconducting coherence peak and the pseudogap hump coexisted, implying that the two gaps are of separate origins. The hump voltage increased below T c , following the superconducting gap voltage, which led to the conclusion that the hump structure below T c in our ITS arose from the combined contributions of the quasiparticle spectral weights of two different characters: one of the superconducting state and another of the PG state near the antinodal region.

Temperature dependence of the bulk energy gap in underdopedBi2Sr2CaCu2O8+δKrasnov1 2009Phys. Rev. B489430View full textAdd to dashboardCite

“…Interlayer tunneling occurs in various layered HTSC compounds, such as Bi-2212 [15,26,27,36,37,38], Bi-2201 [39], Tl-2212 [40,41] YBaCuO [42], and some others [43], as well as in intercalated compounds [44]. ITS was also expanded to non-HTSC layered compounds [45,46].…”

“…Detailed analysis of self-heating in ITS, including numerical simulations of distortion of IVCs by self-heating can be found in Appendix-A. In recent years different ways of obviating self-heating in ITS were employed, such as pulse measurements [36], miniaturization [50,59] and heat compensation [37]. In Ref.…”

Axion field and the quark nugget’s formation at the QCD phase transition

“…One should emphasize once again that the generic consequences of the framework represented by (1), (65) are not sensitive to any specific parameters such as efficiency of the domain wall production or the magnitude of θ at the QCD phase transition, which could be quite small, see footnote 13 with few comments on that. Nevertheless, precisely the coupling with the coherent CP odd axion field plays a crucial role in generation of |c(T )| = 1, i.e.…”

“…For example, if c(T form ) −2 then the corresponding relation (65) between the dark matter and the visible matter would assume the form Ω dark 3 · Ω visible . Such a relation implies that there is a plenty of room for other types of dark matter to saturate the observed ratio Ω observed dark 5 · Ω observed visible .…”

“…(62), (64), (65) takes the following form at this time T form for c(T form ) −1.5 which corresponds to the case when the nuggets saturate entire dark matter density:…”