Condensed Matter/Materials & Biological Physics Seminar with Daniel Hill on Topology in unexpected places: Emergent quasiparticle kinetics in nanomagnets and soliton screened spin superfluids.

I will present the results of a joint experimental and theoretical project studying artificial magnetic honeycomb nanostructures. Neutron spin echo measurements of honeycomb spin ice nanostructures made of permalloy find persistent temperature-independent (up to room temperature) magnetic dynamics on a timescale of 20 ns. Similar findings unexpectedly occur in honeycomb nanostructures made of antiferromagnetic neodymium. Theoretical modeling suggests that both measurements can be explained by the presence of frustration stabilized nanoscale topological quasiparticles with the profile of a half skyrmion. The presence of the same dynamics in vastly different materials and across a broad range of temperatures suggests the possibility of a new form of highly universal nanoscale topological quasiparticle kinematics. If confirmed, this discovery could point the way to new forms of spintronics based computing. Following this I will discuss another unexpected (and in this case more likely counterproductive) emergence of topology in the case of the solution screened spin superfluid.

Hill is a Postdoctoral Researcher at the University of Missouri's Department of Physics & Astronomy. He specializes in topics including magnetization, spintronics, thin film magnetism, superconductivity, and thin films and nanotechnology.

This lecture was made possible by the William C. Ferguson Fund