Dr. Pablo Burset (Nagoya University)
"Manipulation of the induced pair potential in topological insulator-superconductor hybrid junctions"
The interplay between the spin-orbit coupling at the surface of a topological insulator (TI), the conventional pair potential
from a superconductor, and an external magnetic field creates a very exotic induced pair potential in a TI-based normal-superconductor
junction. In addition to a superposition of spin-singlet and triplet components, a new, unconventional type of superconducting
condensate can be induced in this system: one with a spin-triplet component that is both odd in frequency and even in its
spatial coordinates.
We propose a detection scheme for the odd-frequency triplet based on nonlocal conductance measurements on the one-dimensional
edge of a two-dimensional TI: we show a one-to-one correspondence between crossed Andreev reflection processes and the emergence
of odd-frequency triplet superconductivity [1].
We also consider the proximity effect on a three-dimensional TI-superconductor junction under the effect of an external magnetic
field [2]. We find that the magnetic field induces even- and odd-frequency spin-triplet terms in the pairing amplitude, which are
always superposed with an even-frequency spin-singlet term. The competition between all these components results in a rich subgap
structure with emerging zero-energy peaks. Using very basic ingredients such as a conventional superconductor and an external
magnetic field, standard experimental techniques like conductance spectroscopy can be used to detect signatures of odd-frequency
superconductivity.
References:
[1] F. Crepin, P. Burset, B. Trauzettel, Phys. Rev. B 92, 100507(R) (2015).
[2] P. Burset, B. Lu, G. Tkachov, Y. Tanaka, E.M. Hankiewicz, B. Trauzettel, Phys. Rev. B 92, 205424 (2015).