A two-dimensional superconducting electron gas in freestanding LaAlO3/SrTiO3 micro-membranes

DOI: 10.1021/acs.nanolett.2c00992

R. Erlandsen, R. T. Dahm, F. Trier, M. Scuderi, E. Di Gennaro, A. Sambri, C. Kirchert, N. Pryds F. Miletto Granozio, T. S. Jespersen
Year of Publication: 2022

Freestanding oxide membranes constitute an intriguing material platform for new functionalities and allow integration of oxide electronics with technologically important platforms such as silicon. Sambri et al. recently reported a method to fabricate freestanding LaAlO3/SrTiO3 (LAO/STO) membranes by spalling of strained heterostructures. Here, we first develop a scheme for the high-yield fabrication of membrane devices on silicon. Second, we show that the membranes exhibit metallic conductivity and a superconducting phase below ∼200 mK. Using anisotropic magnetotransport we extract the superconducting phase coherence length ξ ≈ 36–80 nm and establish an upper bound on the thickness of the superconducting electron gas d ≈ 17–33 nm, thus confirming its two-dimensional character. Finally, we show that the critical current can be modulated using a silicon-based backgate. The ability to form superconducting nanostructures of LAO/STO membranes, with electronic properties similar to those of the bulk counterpart, opens opportunities for integrating oxide nanoelectronics with silicon-based architectures.

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