Tuesday, September 26, 2017 at 12:20pm to 1:45pm
Clark Hall, 700
Mark Freeman, Department of Condensed Matter Physics, University of Alberta, Edmonton, AB, Canada, will present seminar. Professor Jeevak Parpia, host.
Seminar Title: Nanomagnetism with torsional optomechanics
Abstract: Applications of an emerging nanomechanical lab-on-a-chip for magnetism are presented. Sensitive measurements of magnetic hysteresis for a single magnetic vortex in Permalloy enable quantitative mapping of the energetics underlying domain-wall pinning and Barkhausen noise. The position-dependent energy of the spin texture is resolved with nanometer- and 0.1 eV-scale resolutions. This facilitates local tailoring of magnetic properties for the creation of ‘designer’ hysteresis loops .
Magnetic resonance spectroscopy of spin dynamics in small structures is among the lab-on-a-chip capabilities. Magnetic torque is used as a signal mixer, converting the transverse component of a resonantly-precessing RF moment into a mechanically-resonant twist on the torque sensor. Broadband ferrimagnetic resonance spectra of a single-crystal, mesoscopic yttrium iron garnet disk demonstrate the power of the technique .
The phase space for application of the l-o-c approach expands with advances in the state-of-the-art for nanomechanics. Dramatic gains are suggested by magnetic measurements utilizing nanocavity optomechanics .
 JAJ Burgess et al., “Quantitative magneto-mechanical detection and control of the Barkhausen effect”, Science 339, 1051 (2013).
 JE Losby et al., “Torque-mixing magnetic resonance spectroscopy”, Science 350, 798(2015).
 M Wu et al., “Nanocavity optomechanical torque magnetometry and radiofrequency susceptometry”, Nature Nanotech. 12, 127 (2017).