Side Gate Tunable Josephson Junctions at the LaAlO 3 /SrTiO 3 Interface

• Published in: Nano letters Vol. 17; no. 2; pp. 715 - 720
• Main Authors: Monteiro, A M R V L, Groenendijk, D J, Manca, N, Mulazimoglu, E, Goswami, S, Blanter, Ya, Vandersypen, L M K, Caviglia, A D
• Format: Journal Article
• Language: English
• Published: United States 08-02-2017
• Subjects: Oxide heterostructures; side gates; Josephson junction; SQUID; field-effect
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.6b03820

Novel physical phenomena arising at the interface of complex oxide heterostructures offer exciting opportunities for the development of future electronic devices. Using the prototypical LaAlO
/SrTiO
interface as a model system, we employ a single-step lithographic process to realize gate-tunable Josephson junctions through a combination of lateral confinement and local side gating. The action of the side gates is found to be comparable to that of a local back gate, constituting a robust and efficient way to control the properties of the interface at the nanoscale. We demonstrate that the side gates enable reliable tuning of both the normal-state resistance and the critical (Josephson) current of the constrictions. The conductance and Josephson current show mesoscopic fluctuations as a function of the applied side gate voltage, and the analysis of their amplitude enables the extraction of the phase coherence and thermal lengths. Finally, we realize a superconducting quantum interference device in which the critical currents of each of the constriction-type Josephson junctions can be controlled independently via the side gates.