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 Karl Franzens University Graz

Graz University of Technology 

Oxide heterostructures: from efficient solar cells to spin-orbit coupling
UP Dr. Karsten Held
Professor of Computational Materials Science Institute for Solid State Physics, TU Wien
17:15 - 18:15 Tuesday 25 June 2013 TUG P2


Heterostructures made of transition metal oxides are an upcoming class of materials which may replace at some point conventional semiconductors for specific applications. Unexpected physics emerges: For example the interface between two insulators turns metallic.

We show how to exploit the unique properties of these heterostructures for high-efficiency solar cells [1]: The intrinsic electric field of polar heterostructures allows for efficiently separating the created electrons and holes. Furthermore, the heterostructure naturally provides electrical contacts through ultra-thin conducting interface layers. Last but not least, the bandgap in some heterostructures is optimal for the solar spectrum and can be tuned by using different chemical elements layer-by-layer.

In the second part, I will present the theory of spin-orbit coupling in oxide heterostructures [2] which, due to multi-orbital effects, is strikingly different from the standard Rashba theory of semiconductor heterostructures: By far the biggest effect is at the crossing point of the x-y and y-z orbitals; around the Gamma point a spin splitting with a linear and cubic dependence on the wave vector k is possible.


[1] E. Assmann et al., Phys. Rev. Lett. 110, 078701 (2013).
[2] Z. Zhong, A. Toth, and K. Held, arXiv:1209.4705