Dresden 2017 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 45: Electronic-Structure Theory: New Concepts and Developments in Density Functional Theory and Beyond - IV (joint session DS, HL, MA, MM, O, TT, organized by O)

TT 45.6: Vortrag

Mittwoch, 22. März 2017, 12:00–12:15, GER 38

Conditions for formation of two-dimensional electron gas at the LaFeO₃/SrTiO₃ — •Igor Maznichenko¹, Sergey Ostanin¹, Arthur Ernst², Ingrid Mertig^1,2, Katayoon Mohseni², Holger L. Meyerheim², Eberhard K.U. Gross², Pengfa Xu³, Wei Han³, Philip M. Rice³, Jaewoo Jeong³, Mahesh G. Samant³, and Stuart S.P. Parkin^2,3 — ¹Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, D-06099 Halle, Germany — ²Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany — ³IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA

The formation of a conducting two dimensional electron gas (2DEG) at the interface between two insulating oxide layers was explained theoretically for atomically and chemically abrupt interfaces via polar discontinuity.

Here we show that a 2DEG is formed at the interface between thin layers of lanthanum ferrite, LaFeO₃ (LFO), that are more than 3 unit cells thick, when grown epitaxially on SrTiO₃ (STO) (001). The interface property highly depends on the surface property of TiO₂ terminated STO. The interface is conducting if the STO is not annealed in an oxygen environment prior to the LFO growth, while insulating if the STO is annealed.

First principles calculations reveal that a 2DEG should be realized for an ideal interface but that modest chemical intermixing suppresses it. These calculations also show that the presence of oxygen vacancies supports 2DEG formation due to electronic doping.