Regensburg 2010 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 19: CE: Metal-Insulator Transition 2

TT 19.12: Talk

Wednesday, March 24, 2010, 12:45–13:00, H18

Electronic reconstruction in thin LaAlO₃ films on SrTiO₃(001) via a SrTiO₃-capping layer — •Katrin Otte¹, Rossitza Pentcheva¹, and Warren E. Pickett² — ¹Section Crystallography, Dept. of Earth and Environmental Sciences, University of Munich — ²Department of Physics, UC Davis

Novel electronic phenomena can be realized at the interface between polar (e.g. LaAlO₃) and nonpolar (e.g. SrTiO₃) band insulators. An intriguing example is the thickness dependent insulator-to-metal transition in thin LaAlO₃ films on SrTiO₃(001)[1]. Density functional theory calculations show that a strong lattice polarization allows several layers of LaAlO₃ on SrTiO₃(001) to remain insulating before an insulator-to-metal transition takes place at around 4 monolayers (MLs)[2]. We demonstrate here that an additional capping SrTiO₃ can trigger the electronic reconstruction already at two MLs of LaAlO₃. A surface O 2p state, similar to the surface states in SrTiO₃, is identified as the origin of this additional band shift.

Altogether, the SrTiO₃-capping layer represents an alternative pathway to tune the electronic reconstruction of the system leading to the formation of an electron-hole bilayer.

[1] S. Thiel et al., Science 313, 1942 (2006).

[2] R. Pentcheva and W.E. Pickett, Phys. Rev. Lett. 102, 107602 (2009).