Jens Wiebe

Academic Affiliation: University of Hamburg

This lecture is intended for Master and PhD students as well as young Postdocs. After a short historical review of
the discoveries of materials which are conventional and unconventional superconductors, I will give an
introduction to Cooper pairing and the Bardeen–Cooper–Schrieffer (BCS) theory, the microscopic theory for the
description of conventional superconductivity. Then, I will describe the quasiparticle excitation spectrum of such
a superconductor and explain how it can be experimentally measured using scanning tunnel spectroscopy, both
with normal-metal and superconducting tips. Subsequently, I will talk about the effects of magnetic fields and
single magnetic impurities on a superconducting substrate, where the latter leads to the so-called Yu-ShibaRusinov bound states. Finally, I will explain different strategies to tailor a topological superconductor, including
the spin chain platform where bands formed by the hybridization of Yu-Shiba-Rusinov states in chains of magnetic
atoms in contact to a superconducting surface can host Majorana bound states.

Literature

C. Enss and S. Hunklinger, Low Temperature Physics (Springer 2005)
R. Gross and A. Marx, Festkörperphysik (De Gruyter 2014): unfortunately only in german so far…
Several original publications