Retention of Electronic Conductivity in LaAlO3/SrTiO3 Nanostructures Using a SrCuO2 Capping Layer
2016 (English)In: PHYSICAL REVIEW APPLIED, ISSN 2331-7019, Vol. 6, no 2, 024011Article in journal (Refereed) Published
The interface between two wide band-gap insulators, LaAlO3 and SrTiO3 (LAO/STO) offers a unique playground to study the interplay and competitions between different ordering phenomena in a strongly correlated two- dimensional electron gas. Recent studies of the LAO/STO interface reveal the inhomogeneous nature of the 2DEG that strongly influences electrical-transport properties. Nanowires needed in future applications may be adversely affected, and our aim is, thus, to produce a more homogeneous electron gas. In this work, we demonstrate that nanostructures fabricated in the quasi-2DEG at the LaAlO3/SrTiO3 interface, capped with a SrCuO2 layer, retain their electrical resistivity and mobility independent of the structure size, ranging from 100 nm to 30 mu m. This is in contrast to noncapped LAO/STO structures, where the room-temperature electrical resistivity significantly increases when the structure size becomes smaller than 1 mu m. High-resolution intermodulation electrostatic force microscopy reveals an inhomogeneous surface potential with "puddles" of a characteristic size of 130 nm in the noncapped samples and a more uniform surface potential with a larger characteristic size of the puddles in the capped samples. In addition, capped structures show superconductivity below 200 mK and nonlinear currentvoltage characteristics with a clear critical current observed up to 700 mK. Our findings shed light on the complicated nature of the 2DEG at the LAO/STO interface and may also be used for the design of electronic devices.
Place, publisher, year, edition, pages
American Physical Society , 2016. Vol. 6, no 2, 024011
IdentifiersURN: urn:nbn:se:kth:diva-193441DOI: 10.1103/PhysRevApplied.6.024011ISI: 000381486000002OAI: oai:DiVA.org:kth-193441DiVA: diva2:1034597
FunderSwedish Research CouncilKnut and Alice Wallenberg FoundationSwedish Institute
QC 201610122016-10-122016-10-032016-10-12Bibliographically approved