Temperature and field dependence of the intrinsic tunnelling structure in overdoped Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+\delta }$

Abstract

We report intrinsic tunnelling data for mesa structures fabricated on three over- and optimally-doped $\mathrm{B}{\mathrm{i}}_{2.15}\mathrm{S}{\mathrm{r}}_{1.85}\mathrm{CaC}{\mathrm{u}}_2{\mathrm{O}}_{8+\delta }$ crystals with transition temperatures of 86-78~K and 0.16-0.19~holes per CuO${}_2$ unit, for a wide range of temperature ($T$) and applied magnetic field ($H$), primarily focusing on one over-doped crystal(OD80). The differential conductance above the gap edge shows clear dip structure which is highly suggestive of strong coupling to a narrow boson mode. Data below the gap edge suggest that tunnelling is weaker near the nodes of the d-wave gap and give clear evidence for strong $T$-dependent pair breaking. These findings could help theorists make a detailed Eliashberg analysis and thereby contribute towards understanding the pairing mechanism. We show that for our OD80 crystal the gap above $T_c$ although large, is reasonably consistent with the theory of superconducting fluctuations.

15 pages, 15 figures plus supplemental material, 1 table and 47 ASCII files with raw data. Corrected files for Fig. 12a

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Cited by in corpus (3)

• Locating the pseudogap closing point in cuprate superconductors: absence of entrant or reentrant behavior
• Incoherent superconductivity well above $T_c$ in high-$T_c$ cuprates - harmonizing the spectroscopic and thermodynamic data
• Field-dependent specific heat of the canonical underdoped cuprate superconductor YBa${}_2$Cu${}_4$O${}_8$