Zero-bias anomaly in a nanowire quantum dot coupled to superconductors
| Autor: | Lee, Eduardo J. H., Jiang, Xiaocheng, Aguado, Ramon, Katsaros, Giorgos, Lieber, Charles M., De Franceschi, Silvano |
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| Rok vydání: | 2012 |
| Předmět: | |
| Zdroj: | Phys. Rev. Lett. 109, 186802 (2012) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevLett.109.186802 |
| Popis: | We studied the low-energy states of spin-1/2 quantum dots defined in InAs/InP nanowires and coupled to aluminium superconducting leads. By varying the superconducting gap, \Delta, with a magnetic field, B, we investigated the transition from strong coupling, \Delta << T_{K}, to weak coupling, \Delta >> T_{K}, where T_{K} is the Kondo temperature. Below the critical field, we observe a persisting zero-bias Kondo resonance that vanishes only for low B or higher temperatures, leaving the room to more robust sub-gap structures at bias voltages between \Delta and 2\Delta. For strong and approximately symmetric tunnel couplings, a Josephson supercurrent is observed in addition to the Kondo peak. We ascribe the coexistence of a Kondo resonance and a superconducting gap to a significant density of intra-gap quasiparticle states, and the finite-bias sub-gap structures to tunneling through Shiba states. Our results, supported by numerical calculations, own relevance also in relation to tunnel-spectroscopy experiments aiming at the observation of Majorana fermions in hybrid nanostructures. Comment: 11 pages, 7 figures |
| Databáze: | arXiv |
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