Nanoscale control of an interfacial metal-insulator transition at room temperature

• Published in: Nature materials Vol. 7; no. 4; pp. 298 - 302
• Main Authors: Levy, J, Cen, C, Thiel, S, Hammerl, G, Schneider, C. W, Andersen, K. E, Hellberg, C. S, Mannhart, J
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.04.2008; Nature Publishing Group
• Subjects: Biomaterials; Chemistry and Materials Science; Condensed Matter Physics; Electric fields; Electronics; Gases; Islands; letter; Materials Science; Nanotechnology; Optical and Electronic Materials; Phase transitions; Physics; Semiconductor doping
• ISSN: 1476-1122; 1476-4660
• DOI: 10.1038/nmat2136

Experimental and theoretical investigations have demonstrated that a quasi-two-dimensional electron gas (q-2DEG) can form at the interface between two insulators: non-polar SrTiO3 and polar LaTiO3 (ref. 2), LaAlO3 (refs 3-5), KTaO3 (ref. 7) or LaVO3 (ref. 6). Electronically, the situation is analogous to the q-2DEGs formed in semiconductor heterostructures by modulation doping. LaAlO3/SrTiO3 heterostructures have recently been shown to exhibit a hysteretic electric-field-induced metal-insulator quantum phase transition for LaAlO3 thicknesses of 3 unit cells. Here, we report the creation and erasure of nanoscale conducting regions at the interface between two insulating oxides, LaAlO3 and SrTiO3. Using voltages applied by a conducting atomic force microscope (AFM) probe, the buried LaAlO3/SrTiO3 interface is locally and reversibly switched between insulating and conducting states. Persistent field effects are observed using the AFM probe as a gate. Patterning of conducting lines with widths of ∼3 nm, as well as arrays of conducting islands with densities >1014 inch−2, is demonstrated. The patterned structures are stable for >24 h at room temperature.