title: Emergent nanoscale superparamagnetism at oxide interfaces.
abstract: Atomically sharp oxide heterostructures exhibit a range of novel physical phenomena that are absent in the parent compounds. A prominent example is the appearance of highly conducting and superconducting states at the interface between LaAlO3 and SrTiO3. Here we report an emergent phenomenon at the LaMnO3/SrTiO3 interface where an antiferromagnetic Mott insulator abruptly transforms into a nanoscale inhomogeneous magnetic state. Upon increasing the thickness of LaMnO3, our scanning nanoSQUID-on-tip microscopy shows spontaneous formation of isolated magnetic nanoislands, which display thermally activated moment reversals in response to an in-plane magnetic field. The observed superparamagnetic state manifests the emergence of thermodynamic electronic phase separation in which metallic ferromagnetic islands nucleate in an insulating antiferromagnetic matrix. We derive a model that captures the sharp onset and the thickness dependence of the magnetization. Our model suggests that a nearby superparamagnetic-ferromagnetic transition can be gate tuned, holding potential for applications in magnetic storage and spintronics.
authors: Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
authors: Y
authors: Y
authors: Anahory
authors: Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
authors: L
authors: L
authors: Embon
authors: NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore.|NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore.
authors: C J
authors: CJ
authors: Li
authors: Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
authors: S
authors: S
authors: Banerjee
authors: Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
authors: A
authors: A
authors: Meltzer
authors: Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
authors: H R
authors: HR
authors: Naren
authors: Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
authors: A
authors: A
authors: Yakovenko
authors: Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
authors: J
authors: J
authors: Cuppens
authors: Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
authors: Y
authors: Y
authors: Myasoedov
authors: Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
authors: M L
authors: ML
authors: Rappaport
authors: Departments of Physics and Electrical Engineering, University of Colorado Denver, Denver, Colorado 80217, USA.
authors: M E
authors: ME
authors: Huber
authors: Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
authors: K
authors: K
authors: Michaeli
authors: NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore.|NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore.|Department of Physics, National University of Singapore, Singapore 117542, Singapore.|Department of ECE and MSE, National University of Singapore, Singapore 117576, Singapore.
authors: T
authors: T
authors: Venkatesan
authors: NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore.|NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore.|Department of Physics, National University of Singapore, Singapore 117542, Singapore.
authors: Ariando
authors: Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
authors: E
authors: E
authors: Zeldov