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

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

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.