Tuning Transport and Magnetism at Polar Oxide Interfaces

Date: 
04/06/2021 - 3:30pm to 5:00pm
Location: 
Zoom
Speaker(s) / Presenter(s): 
Professor Divine Kumah

Prof. Divine Kumah

Department of Physics

North Carolina State University

Host: Gannon

Title: Tuning Transport and Magnetism at Polar Oxide Interfaces

Abstract: Atomic-scale interactions at the interfaces between polar and non-polar transition metal oxides have led to the realization of exciting phenomena including two-dimensional electron gases, superconductivity and interfacial magnetism. However, these interactions may lead to the suppression of electronic and magnetic ordering at interfaces with strong structure-property relationships. By imaging the atomic structure of the interface between polar LaSrMnO3 (LSMO) and non-polar SrTiO3, we identify interfacial structural distortions which are correlated with thickness-dependent metal-insulator and ferromagnetic-paramagnetic transitions in the rare-earth manganites. We show that these structural distortions can be tuned by inserting polarity-matched spacer layers at the LSMO interfaces leading to a stabilization of ferromagnetism in LSMO layers as thin as two unit cells. The stabilized magnetism is found to be independent of strain. We employ a combination of synchrotron X-ray diffraction, temperature-dependent magnetization measurements and X-ray magnetic circular dichroism to elucidate the interplay between structural and spin degrees of freedom in the rare-earth manganites.[1,2] Additionally, we find that by tuning growth and post-growth processing conditions, a two-dimensional electron gas (2DEG) forms at the interface between antiferromagnetic LaCrO3 and SrTiO3 providing a route to design all-oxide heterostructures which couple magnetic ordering with the mobile carriers within the 2DEG.[3] These results demonstrate the intimate role of picometer-scale structural distortions on the physical properties of transition metal oxides and have important implications for designing novel quantum materials.


References

[1] Koohfar et. al., npj Quantum Materials 4 (1), 25 (2019)
[2] Koohfar et. al., Physical Review B 101 (6), 064420 (2020)
[3] Al-Tawhid et. al., AIP Advances 10 (4), 045132 (2020)