Seminar “Theory of Condensed Matter”

Date and Time: Tuesday, 5 April 2022, at 4:00 PM

Venue: Blokhintsev lecture hall, Bogoliubov Laboratory of Theoretical Physics, online seminar on Zoom

Link to join the seminar via Zoom

Seminar topic: “Features of the density of states in S/N bilayers”

Authors: A. A. Mazanik, Ya. V. Fominov

Speaker: A. A. Mazanik (MIPT and BLTP)

Abstract:

We study the density of states (DoS) ν in a superconductor/normal metal bilayer with a transparent S/N interface. We have found two different types of the DoS behavior at energy E equal to the superconducting bulk order parameter ∆₀: a monotonic vertical peculiarity with divergent derivatives ∂ν/∂E at E → ∆₀ ± 0 and a check-mark peculiarity characterized by ν(E = ∆₀) = 0.

The crossover between the two regimes (first discussed in Refs. [1] and [2], respectively) is controlled by the strength of the inverse proximity effect: if the inverse proximity effect is completely absent, then we find ν(E = ∆₀) = 0 as long as the normal layer is thinner than the critical thickness dN (cr) ≈ 2.858 ξN with ξN being the coherence length in the normal metal. When the inverse proximity effect comes into play, we find that ν(E = ∆₀) immediately becomes finite and the DoS behavior gradually evolves to the vertical peculiarity.

Sourcers:

[1] Ya. V. Fominov, A. Mazanik, and M. Razumovskiy, Physical Review B 100, 224513 (2019).
[2] A. Levchenko, Physical Review B 77, 180503 (2008).