YRLG Workshop: Correlation and Topology in magnetic materials, July 16th - 18th 2024
Noah Kent
Topological magnetic structures, i.e. Skyrmions and Hopfions, are undergoing thorough research in solid state condensed matter systems and soft matter systems due to their technological potential and the fundamental physics they probe.1,2 In this talk I will discuss how topological magnetic structures manifest themselves in biological systems in two different ways: (1) topological magnetic nanostructures that are useful for manipulating biological systems and (2) generating topological structures using magnetic fields in systems where the order parameter is the velocity vector of a living entity.
- Magnetic nanotransducers are magnetic nanoparticles which convert an applied alternating magnetic field into stimuli that interact with biological systems. Typically this is heat or mechanical torque, but these stimuli require specific ion channels which can “feel” them.3 Since electric stimulation can trigger all neuronal systems, we have developed artificial magnetoelectric nanodisks composed of a magnetostrictive magnetite vortex core (w = ½), layered with CoFe2O4, and the piezoelectric BaTiO3. I will discuss the design decisions, supported by MuMax3 magnetoelastic simulations, that allow these magnetoelectrics to perform orders of magnitude better than other magnetoelectrics in the literature; including the enhancement of the magnetoelectric response due to the vortex state of the magnetostrictive core. These enhanced disks are able to remotely control dopamine release after being implanted in the ventral tegmental area of mice.4
- Magnetotactic bacteria are microorganisms with magnetite organelles, known as magnetosomes, that have a response to external magnetic fields. Despite the magnetic properties of these bacteria being studied for several decades, there has been little success connecting the bacteria’s directional movement to the response of external, uniform, magnetic fields. Utilizing insights gained from nanomagnetic simulations of realistic distributions of magnetosomes observed in magnetotactic bacteria we are able to understand the external field response of individual bacterium based on the arraignment of magnetosomes found inside. This allows us to controllably change the nature of the collective velocity vector of these bacteria from polar to non-polar and control individual bacterium. It is then possible to generate skyrmions in both the polar and nonpolar velocity vector fields of the bacteria using external magnetic fields.
References:
[1] https://doi.org/10.1038/s41467-021-21846-5 [2] https://doi.org/10.1038/natrevmats.2017.31 [3] DOI: 10.1126/science.1261821 [4] https://www.biorxiv.org/content/10.1101/2023.12.24.573272v1