Revealing sign-reversal $s^{+-}$-wave pairing by quasiparticle interference in the heavy-fermion superconductor CeCu${}_2$Si${}_2$

Shan Zhao, Bin Liu, Yi-feng Yang +1

Recent observations of two nodeless gaps in superconducting CeCu${}_2$Si${}_2$ have raised intensive debates as to its exact gap structure of either sign-reversal ($s^{+-}$) or sign-pr…