A Two-Dimensional Superconducting Electron Gas in Freestanding LaAlO3/SrTiO3 Micromembranes

Freestanding oxide membranes constitute an intriguing material platform for new functionalities and allow integration of oxide electronics with technologically important platforms such as silicon, flexible polyethylene terephthalate, and biocompatible polymide.

In 2020, a research team, composed by CNR-SPIN of Naples, CNR-IMM of Catania, Università degli Studi di Napoli Federico II, Niels Bohr Institute, University of Copenhagen and the Technical University of Denmark, reported a method to fabricate freestanding conducting LaAlO3/SrTiO3 (LAO/STO) membranes by spalling of strained heterostructures.

Recently, the same research team further worked on that topic, developing a scheme for the high-yield fabrication of membrane devices on silicon, and then investigating the low-temperature electrical properties of this novel system by measurements of individual membranes incorporated into devices on a Si/SiO2 substrate. They demonstrated the presence of a superconducting phase with a transition temperature of ∼120–250 mK, similar to typical values of bulk LAO/STO. From anisotropic magnetotransport, they extracted the in-plane phase coherence length and set an upper bound of the effective thickness of the interfacial electron gas, confirming its two-dimensional character. Finally, using the doped Si substrate as a gate electrode, they achieved electrostatic tunability of the normal state resistance and of the critical current of the freestanding membranes.

The demonstrated 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.

The results have been published in Nano Letters:

A Two-Dimensional Superconducting Electron Gas in Freestanding LaAlO3/SrTiO3 Micromembranes, Ricci Erlandsen, Rasmus Tindal Dahm, Felix Trier, Mario Scuderi, Emiliano Di Gennaro, Alessia Sambri, Charline Kaisa Reffeldt Kirchert, Nini Pryds, Fabio Miletto Granozio, and Thomas Sand Jespersen, Nano Letters 2022, doi.org/10.1021/acs.nanolett.2c00992

Last modified on Saturday, 18 June 2022 21:56
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