Emergent phenomena in superconductors in presence of intraband and cross-band pairing

Date: 21 January 2020

Venue: UAntwerpen, Campus Groenenborger, G.U. 244 - Groeneborgerlaan 171 - 2020 Antwerpen (route: UAntwerpen, Campus Groenenborger)

Time: 4:00 PM - 5:00 PM

Organization / co-organization: Condensed Matter Theory

Short description: CMT lecture presented by Dr Alfredo Vargas Paredes from CMT

Today's most common superconductors present different energy bands whose electrons can participate in the formation of Cooper pairs. An old question in this context regards the possibility and implications of Cooper pair formation between two electrons belonging to different bands. In this seminar we will present the emergence of new phenomena in multigap superconductors and multicomponent Ginzburg-Landau theories in the presence of intraband and cross-band pairing.

The first part contains a review of emergent phenomena in superconductors with only intraband pairing, in particular the mechanism behind gap resonances which are accompanied by Higgs and Leggett modes. In the second part we describe the conditions where the cross-band pair formation is feasible. Then we will present the signatures and consequences of the inclusion of crosspairing in the BCS-theory and in the Ginzburg-Landau theory.

Some of those signatures are given by the crossover between the intraband-pairing-dominated and crossband-pairing-dominated regimes. These two are delimited by a tendency towards a gapless state in the density of states or vortex cluster formation when a magnetic field is applied. Our theoretical findings are illustrated using two compounds MgB2 and Ba0.6K0.4Fe2As2.

Contact email: lucian.covaci@uantwerpen.be

Link: http://cmt.uantwerpen.be