Observation of Vortex/Meron Pairs at Room Remperature in a planar α-Fe2O3/Co Heterostructure.

CCMMP Seminars
Prof Paolo Radaelli
Martin Dove
January 30th, 2018 at 14:00
GO Jones Room 610

Vortices are among the simplest topological structures, and occur whenever a flow field ‘whirls’ around a one- dimensional core. They are ubiquitous to many branches of physics. In the crystalline state, vortex formation is rare, since it is generally hampered by long-range interactions. I will present the discovery of a novel form of crystalline vortices in antiferromagnetic (AFM) hematite (α-Fe2O3) epitaxial films, in which the primary whirling parameter is the non-ferroics staggered magnetisation. Remarkably, ferromagnetic (FM) topological objects known as half-skyrmions or merons with the same vorticity and winding number of the α-Fe2O3 vortices are imprinted onto an ultra-thin Co ferromagnetic over-layer by exchange proximity. Our data suggest that the vortex/meron pairs are relatively robust well beyond the Co coercive field, but can be manipulated by the application of a larger (H∥ 100mT) in-plane magnetic field H∥, giving rise to large-scale vortex-antivortex annihilation.