Peculiarities of the density of states in SN junctions

Abstract

We study the density of states (DoS) $\nu (E)$ in a normal-metallic (N) film contacted by a bulk superconductor (S). We assume that the system is diffusive and the SN interface is transparent. In the limit of thin N layer (compared to the coherence length), we analytically find three different types of the DoS peculiarity at energy equal to the bulk superconducting order parameter ${\Delta }_0$. (i) In the absence of the inverse proximity effect, the peculiarity has the check-mark form with $\nu ({\Delta }_0)=0$ as long as the thickness of the N layer is smaller than a critical value. (ii) When the inverse proximity effect comes into play, the check-mark is immediately elevated so that $\nu ({\Delta }_0)>0$. (iii) Upon further increasing of the inverse proximity effect, $\nu (E)$ gradually evolves to the vertical peculiarity (with an infinite-derivative inflection point at $E={\Delta }_0$). This crossover is controlled by a materials-matching parameter which depends on the relative degree of disorder in the S and N materials.

arXiv comment20 pages, 8 figures. Version 2: updated Introduction and Conclusions, added Discussion section (on experimental relevance) and references. Final version as published in Annals of Physics

References in corpus (19)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Quasiclassical Green's function approach to mesoscopic superconductivity
• Local Density of States in a Dirty Normal Metal connected to a Superconductor
• Phase controlled superconducting proximity effect probed by tunneling spectroscopy
• Density of states and supercurrent in diffusive SNS junctions: role of nonideal interfaces and spin-flip scattering
• Proximity Effect and Multiple Andreev Reflections in Diffusive SNS Junctions
• On the use of STM superconducting tips at very low temperatures
• Surface impedance and optimum surface resistance of a superconductor with imperfect surface
• Field-dependent nonlinear surface resistance and its optimization by surface nano-structuring in superconductors
• Microscopic interpretation of the Dynes formula for the tunneling density of states
• Local spectroscopy of a proximity superconductor at very low temperature
• Kinetic equation approach to diffusive superconducting hybrid devices
• Tunnel Spectroscopy of a Proximity Josephson Junction
• Spatially resolved spectroscopy on a superconducting proximity structure
• Mesoscopic proximity effect probed through superconducting contacts
• "Smile"-gap in the density of states of a cavity between superconductors
• Josephson currents in chaotic quantum dots
• Secondary "Smile"-gap in the density of states of a diffusive Josephson junction for a wide range of contact types
• Surface density of states in superconductors with inhomogeneous pairing constant: Analytical results