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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