The LaAlO₃/SrTiO₃ (LAO/STO) interface supports a two dimensional electron gas (2DEG), that can be effectively tuned by an electrostatic field^1,2. Sample averaging measurements have shown that electrostatic gating tunes the carrier density, mobility, and dimensionality of the 2DEG^3-5. Local studies have previously found that conductivity is modulated over nanoscale domain walls^6,7.

We use scanning Superconducting QUantum Interference Device (SQUID) to image the field lines generated by local current flow in LAO/STO, and extract the distribution of currents, and its response to an electrostatic field. I will describe the dramatic spatial changes to the conduction at the interface that are caused by the electrostatic field, and discuss the interplay between defects and gating.

References

1.             Thiel, S., Hammerl, G., Schmehl, A., Schneider, C. W. & Mannhart, J. Tunable quasi-two-dimensional electron gases in oxide heterostructures. Science 313, 1942–1945 (2006).

2.             Caviglia, A. D. et al. Electric field control of the LaAlO3/SrTiO3 interface ground state. Nature 456, 624–627 (2008).

3.             Bell, C. et al. Dominant Mobility Modulation by the Electric Field Effect at the LaAlO3/SrTiO3 Interface. Phys. Rev. Lett. 103, (2009).

4.             Caviglia, A. D. et al. Two-Dimensional Quantum Oscillations of the Conductance at LaAlO3/SrTiO3 Interfaces. Phys. Rev. Lett. 105, (2010).

5.             Ben Shalom, M., Ron, A., Palevski, A. & Dagan, Y. Shubnikov–De Haas Oscillations in SrTiO3/LaAlO3 Interface. Phys. Rev. Lett. 105, 206401 (2010).

6.             Kalisky, B. et al. Locally enhanced conductivity due to the tetragonal domain structure in LaAlO3/SrTiO3 heterointerfaces. Nat. Mater. 12, 1091–1095 (2013).

7.             Honig, M. et al. Local electrostatic imaging of striped domain order in LaAlO3/SrTiO3. Nat. Mater. 12, 1112–1118 (2013).