Atomically sharp oxide heterostructures exhibit a range of novel physical phenomena that do not occur in the parent bulk compounds including conducting, superconducting, and magnetic states. We present a new emergent phenomenon at the LaMnO3/SrTiO3 interface in which an antiferromagnetic insulator abruptly transforms into a superparamagnetic state. Above a critical thickness of LaMnO3 of five unit cells, our scanning nanoSQUID-on-tip microscopy  shows spontaneous formation of isolated magnetic islands with in-plane moment of 10^4 to 10^5 μ_B with characteristic diameter of 10 to 50 nm . The nanoscale islands display superparamagnetic dynamics of random moment reversals by thermal activation or in response to an in-plane magnetic field. We propose a charge reconstruction model of the polar LaMnO3/SrTiO3 heterostructure which describes a sharp emergence of thermodynamic phase separation leading to nucleation of metallic ferromagnetic islands in an insulating antiferromagnetic matrix. The model suggests that a gate tunable superparamagnetic-ferromagnetic transition can be induced, holding potential for applications in magnetic storage and spintronics.
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Eli Zeldov, "Emergent nanoscale superparamagnetism and electronic phase separation at oxide interfaces (Conference Presentation)," Proc. SPIE 10357, Spintronics X, 103570W (Presented at SPIE Nanoscience + Engineering: August 07, 2017; Published: 19 September 2017); https://doi.org/10.1117/12.2277911.5581366891001.
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Study of self-shadowing effect as a simple means to realize nanostructured thin films and layers with special attentions to birefringent obliquely deposited thin films and photo-luminescent porous silicon