Shiba Bound States across the Mobility Edge in Doped InAs Nanowires

Alexandre Assouline (1) , Chéryl Feuillet-Palma (1) , Alexandre Zimmers (1) , Hervé Aubin (1) , Marco Aprili (2) , Jean-Christophe Harmand (3)

1 LPEM - Laboratoire de Physique et d'Etude des Matériaux (UMR 8213)
2 LPS - Laboratoire de Physique des Solides
3 C2N - Centre de Nanosciences et de Nanotechnologies [Marcoussis]

We present a study of Andreev quantum dots fabricated with small-diameter (30 nm) Si-doped InAs nanowires where the Fermi level can be tuned across a mobility edge separating localized states from delocalized states. The transition to the insulating phase is identified by a drop in the amplitude and width of the excited levels and is found to have remarkable consequences on the spectrum of superconducting subgap resonances. While at deeply localized levels only quasiparticle cotunneling is observed, for slightly delocalized levels Shiba bound states form and a parity-changing quantum phase transition is identified by a crossing of the bound states at zero energy. Finally, in the metallic regime, single Andreev resonances are observed.

Domaines: Physique [physics]

Alexandre Assouline, Chéryl Feuillet-Palma, Alexandre Zimmers, Hervé Aubin, Marco Aprili, et al.. Shiba Bound States across the Mobility Edge in Doped InAs Nanowires. Physical Review Letters, 2017, 119 (9), pp.097701. ⟨10.1103/PhysRevLett.119.097701⟩. ⟨hal-01611648⟩