Thermal-strain-engineered ferromagnetism of LaMnO3/SrTiO3 heterostructures grown on silicon

Binbin Chen, Nicolas Gauquelin, Pim Reith, Ufuk Halisdemir, Daen Jannis, Matjaz Spreitzer, Mark Huijben, Stefan Abel, Jean Fompeyrine, Johan Verbeeck, Hans Hilgenkamp, Guus Rijnders, Gertjan Koster*

*Corresponding author for this work

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Abstract

The integration of oxides on Si remains challenging, which largely hampers the practical applications of oxide-based electronic devices with superior performance. Recently, LaMnO3/SrTiO3 (LMO/STO) heterostructures have gained renewed interest for the debating origin of the ferromagnetic-insulating ground state as well as for their spin-filter applications. Here we report on the structural and magnetic properties of high-quality LMO/STO heterostructures grown on silicon. The chemical abruptness across the interface was investigated by atomic-resolution scanning transmission electron microscopy. The difference in the thermal expansion coefficients between LMO and Si imposed a large biaxial tensile strain to the LMO film, resulting in a tetragonal structure with c/a∼0.983. Consequently, we observed a significantly suppressed ferromagnetism along with an enhanced coercive field, as compared to the less distorted LMO film (c/a∼1.004) grown on STO single crystal. The results are discussed in terms of tensile-strain enhanced antiferromagnetic instabilities. Moreover, the ferromagnetism of LMO on Si sharply disappeared below a thickness of 5 unit cells, in agreement with the LMO/STO case, pointing to a robust critical behavior irrespective of the strain state. Our results demonstrate that the growth of oxide films on Si can be a promising way to study the tensile-strain effects in correlated oxides, and also pave the way towards the integration of multifunctional oxides on Si with atomic-layer control.
Original languageEnglish
Article number024406
JournalPhysical Review Materials
Volume4
Issue number2
DOIs
Publication statusPublished - 12 Feb 2020

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