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Retention of Electronic Conductivity in LaAlO3/SrTiO3 Nanostructures Using a SrCuO2 Capping Layer

Pier Paolo Aurino (Institutionen för mikroteknologi och nanovetenskap, Kvantkomponentfysik) ; Alexei Kalaboukhov (Institutionen för mikroteknologi och nanovetenskap, Kvantkomponentfysik) ; R. Borgani ; D. B. Haviland ; Thilo Bauch (Institutionen för mikroteknologi och nanovetenskap, Kvantkomponentfysik) ; Floriana Lombardi (Institutionen för mikroteknologi och nanovetenskap, Kvantkomponentfysik) ; Tord Claeson (Institutionen för mikroteknologi och nanovetenskap, Kvantkomponentfysik) ; Dag Winkler (Institutionen för mikroteknologi och nanovetenskap, Kvantkomponentfysik)
Physical Review Applied (2331-7019). Vol. 6 (2016), 2,
[Artikel, refereegranskad vetenskaplig]

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.

Denna post skapades 2016-09-30.
CPL Pubid: 242739


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Institutioner (Chalmers)

Institutionen för mikroteknologi och nanovetenskap, Kvantkomponentfysik



Chalmers infrastruktur