Extraordinary Hall Effect in Freestanding Oxide Heterostructures

Recently, Topological Hall Effect (THE) has been unravelled in various perovskite iridate, ruthenate and manganite interfaces, suggesting the presence of magnetic Skyrmion-like bubbles. Among the materials and sample structures investigated so far, the physical properties were not free from influences of substrates, which are templates for crystalline epitaxial growth. Additional contributions of Dzyaloshinskii-Moriya Interaction or Berry curvatures by the substrates may originate from several structural factors such as in-plane strain, octahedral rotation or terminations. In this report, we employ the water-soluble Sr3Al2O6 sacrificial buffer layer to prepare freestanding SrRuO3/SrIrO3 heterostructures with high-quality interfaces, and THE-like humps are observed up to 90 K. Analysing the Hall signal with the rotation of magnetic field direction suggests there are magnetically decoupled regions. This scheme also paves the way for several magnetic texture imaging techniques in transmission mode for future studies.

Magnetic Anisotropy in [Pt/Co]4/MgO/[Co/Pt]2 Multilayers

A serial of [Pt/Co]4/MgO/[Co/Pt]2multilayers were prepared by magnetron sputtering in this study and Antiferromagnetic (AF) interlayer coupling was observed with increasing MgO spacer thickness. Perpendicular magnetic anisotropy of soft layer in [Pt/Co]4/MgO/[Co/Pt]2multilayers were measured by Extraordinary Hall Effect (EHE). The direction of the magnetic field was parallel to the direction of the current. The results revealed that perpendicular magnetic anisotropy constant Kuoscillates with the thickness of MgO layer which is between 1.3 to 3.3 nm. The period of this oscillation is about 0.43 nm. This is very close to the monolayer (100) MgO. With increasing MgO spacer, the periodic variation of interface between [Pt/Co]nand MgO layer may be one of the reasons for this oscillation behavior of Ku.