2010/06/30 by Lü Li, Lu Li, C. Richter +7 · 2 citations
Engineering · Materials Science · Physics and Astronomy · #Electronic and Structural Properties of Oxides #Ferroelectric and Piezoelectric Materials #Semiconductor materials and devices #cond-mat.mes-hall #cond-mat.mtrl-sci
paper · pdf · doi:10.1126/science.1204168
published as Science 332, 825 (2011) · 4 figures in main text; 4 figures in the supplement
arxiv created 2010/07/12 · openalex publication_date 2011/05/12 · arxiv updated 2015/05/13 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Novel electronic systems forming at oxide interfaces comprise a class of new materials with a wide array of potential applications. A high mobility electron system forms at the LaAlO3/SrTiO3 interface and, strikingly, both superconducts and displays indications of hysteretic magnetoresistance. An essential step for device applications is establishing the ability to vary the electronic conductivity of the electron system by means of a gate. We have fabricated metallic top gates above a conductive interface to vary the electron density at the interface. By monitoring capacitance and electric field penetration, we are able to tune the charge carrier density and establish that we can completely deplete the metallic interface with small voltages. Moreover, at low carrier densities, the capacitance is significantly enhanced beyond the geometric capacitance for the structure. In the same low density region, the metallic interface overscreens an external electric field. We attribute these observations to a negative compressibility of the electronic system at the interface. Similar phenomena have been observed previously in semiconducting two-dimensional electronic systems. The observed compressibility result is consistent with the interface containing a system of mobile electrons in two dimensions.