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DF: Fachverband Dielektrische Festkörper

DF 5: Poster Session on Ferroic Domain Walls - Multiferroics (DF with KR/MA/TT)

DF 5.3: Poster

Montag, 16. März 2015, 19:00–21:00, Poster C

Strain-induced defect-polarization coupling in SrMnO₃ films — •Carsten Becher¹, Laura Maurel², Ulrich Aschauer¹, Martin Lilienblum¹, Cesar Magen², Dennis Meier¹, Eric Langenberg², Morgan Trassin¹, Javier Blasco³, Ingo Krug⁴, Pedro Algarabel³, Nicola Spaldin¹, Jose Pardo², and Manfred Fiebig¹ — ¹ETH Zürich, Zürich, Switzerland — ²Instituto de Nanoscienciencia de Aragon, Zaragoza, Spain — ³Departemento der Fisica de la Materia Condensada, Zaragoza, Spain — ⁴Institut für Optik und Atomare Physik, Berlin, Germany

Epitaxial strain can stabilize new matter phases in thin films and is thus a degree of freedom to increase functionality. Here we demonstrate a novel polar phase in 20 nm SrMnO₃ films that are epitaxially grown under tensile strains by pulsed laser deposition. High resolution X-Ray diffraction and transmission electron microscopy confirm the crystalline quality of the tetragonal films. We use nonlinear optics to proof that strain induces polarity, and density functional theory to show that it simultaneously increases the concentration of oxygen vacancies. These vacancies accumulate at the polar domain walls where they establish an electrostatic barrier to electron migration. As a consequence, scanning probe microscopy shows that the electrical conductance is structured into isolated "nanocapacitors" which can be charged individually.