Tuesday, September 26, 2017 at 12:20pm to 1:45pm

Clark Hall, 700
Central Campus

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 [1].

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 [2].

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 [3]. 

[1] JAJ Burgess et al., “Quantitative magneto-mechanical detection and control of the Barkhausen effect”, Science 339, 1051 (2013).

[2] JE Losby et al., “Torque-mixing magnetic resonance spectroscopy”, Science 350, 798(2015).

[3] M Wu et al., “Nanocavity optomechanical torque magnetometry and radiofrequency susceptometry”, Nature Nanotech. 12, 127 (2017).

Poster available.



Event Type



LASSP, Applied and Engineering Physics, Physics




Contact E-Mail

Contact Name

Douglas E. Milton, Sr.

Contact Phone



Mark Freeman

Speaker Affiliation

University of Alberta


Recent Activity