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O: Fachverband Oberflächenphysik

O 10: Oxides I: Growth and Characterization

O 10.8: Vortrag

Montag, 16. März 2020, 12:15–12:30, WIL B321

Fundamental asymmetry in the electronic reconstruction of polar LaMnO₃/LaAlO₃ vs. LaAlO₃/LaMnO₃ thin films on SrTiO₃(001) — •Benjamin Geisler and Rossitza Pentcheva — Fakultät für Physik, Universität Duisburg-Essen, 47057 Duisburg

Interface polarity plays a key role in oxide heterostructures. Here we explore its effect on the electronic reconstruction in polar LaMnO₃/LaAlO₃ and LaAlO₃/LaMnO₃ thin films on SrTiO₃(001) and show that the materials sequence fundamentally impacts the mechanism. [1] First-principles calculations including a Coulomb repulsion term reveal that for (LaMnO₃)_n/(LaAlO₃)₂/SrTiO₃(001), the electronic reconstruction is triggered already at n=2, and we observe the formation of a two-dimensional electron gas (2DEG) at the SrTiO₃(001) interface with enhanced Ti 3d occupation compared to the (LaAlO₃)₄/SrTiO₃(001) case. Interestingly, in the reversed (LaAlO₃)_m/(LaMnO₃)₃/SrTiO₃(001) system, charge transfer from the surface sets in at m=3, but compensation occurs in the manganate and no 2DEG is formed at the SrTiO₃(001) interface. For lower m=2, no charge transfer is observed at all, highlighting the pivotal role of the materials sequence and thickness. These findings suggest more general design principles of the electronic reconstruction in polar oxide thin films on a nonpolar substrate.

Funding by the DFG within TRR 80 (G3) is acknowledged.

[1] B. Geisler, P. Reith, H. Hilgenkamp, and R. Pentcheva, in preparation