Extreme Enhanced Curie Temperature and Perpendicular Exchange Bias in Freestanding Ferromagnetic Superlattices

Abstract

Most recently, the freestanding of an epitaxial single-crystal oxide has been greatly developed to its fundamental concerns and the possibility of integration with metal, two-dimensional, and organic materials for more promising functionalities. In an artificial ferromagnetic oxide heterostructure and superlattice, the release of the substrate constraint can induce a reasonable transformation of the magnetic structure because the change of the lattice field occurs. In this study, we have comprehensively investigated the evolution of magnetic properties of (La 0.7 Ca 0.3 MnO 3 /SrRuO 3 ) n [(LCMO/SRO) n ] ferromagnetic superlattices while they are epitaxially on SrTiO 3 and freestanding. It is found that the Curie temperature and the perpendicular exchange bias of the freestanding superlattices exhibit extreme sensitivity to the interface number and the thickness of LCMO and SRO, which can maximumly reach ∼293 K and ∼1150 Oe. These enhanced and bulk-beyond magnetic behaviors originate from the interfacial magnetic transition from ferromagnetic to antiferromagnetic via the charge reconstruction with the assistance of strain. Our study provides not only a reference for designing a high-performance flexible ferromagnetic architectural superlattice but also a deep understanding of the interfacial effect in freestanding ferromagnetic heterostructures benefiting flexible spintronics.

Resurrected and Tunable Conductivity and Ferromagnetism in the Secondary Growth La0.7Ca0.3MnO3 on Transferred SrTiO3 Membranes

“…STO (∼10 nm)/Sr 3 Al 2 O 6 (SAO) (∼20 nm) heterostructures were grown on STO substrates using pulsed laser deposition, and freestanding STO (FS-STO) membranes have adhered onto the polydimethylsiloxane (PDMS) supports by taking advantage of the water dissolvable property of SAO. − FS-STO membranes were transferred to STO, Si, and mica substrates, respectively. The XRD patterns of STO/SAO/STO and FS-STO/STO are shown in Figure S1a, and the (002) peak of FS-STO membrane was observed.…”