Chiral magnetic structures in Co/Pd multilayers with a large Dzyaloshinskii-Moriya interaction

  • Shawn Pollard National University of Singapore
Keywords: Magnetism, Electron microscopy, Spin structure


Magnetic skyrmions are local particle-like kinks in the magnetization, previously discovered in a variety of B20 compounds and, more recently, in heavy metal/ferromagnetic bi- and multi-layers. The common factor in these systems is the presence of a large Dzyaloshinskii-Moriya interaction (DMI). This talk focuses on the second class of systems, in which spin-orbit coupling at the heavy metal/ferromagnet interface generates a large enough interaction to stabilize skyrmions and other chiral spin configurations. Specifically, I will discuss our recent work measuring an unexpectedly large DMI in Co/Pd multilayers at room temperature using Kerr microscopy. Through proper tuning of the relative Co and Pd layer thicknesses, as well as repetition number, we demonstrate the emergence of skyrmions at room temperature without a stabilizing external field, necessary in previous multilayer systems to ensure skyrmion stability. Using high resolution Lorentz transmission electron microscopy, we directly image the formation and annihilation processes of these skyrmions, as well as provide evidence for other non-trivial spin textures.

About the Speaker

Shawn Pollard is a research fellow at the Department of Electrical and Computer Engineering at the National University of Singapore.  He received his PhD in Physics from the State University of New York at Stony Brook and he was cited as one of its top graduate students of 2012. His PhD research was carried out at Brookhaven National Laboratory in the Institute for Advanced Electron Microscopy.  His current research focuses on the spin structure and dynamics in systems with strong spin-orbit interactions, as well as magnetic imaging at the nanoscale.