title: Nanocavity optomechanical torque magnetometry and radiofrequency susceptometry.
abstract: Nanophotonic optomechanical devices allow the observation of nanoscale vibrations with a sensitivity that has dramatically advanced the metrology of nanomechanical structures and has the potential to impact studies of nanoscale physical systems in a similar manner. Here we demonstrate this potential with a nanophotonic optomechanical torque magnetometer and radiofrequency (RF) magnetic susceptometer. Exquisite readout sensitivity provided by a nanocavity integrated within a torsional nanomechanical resonator enables observations of the unique net magnetization and RF-driven responses of single mesoscopic magnetic structures in ambient conditions. The magnetic moment resolution is sufficient for the observation of Barkhausen steps in the magnetic hysteresis of a lithographically patterned permalloy island. In addition, significantly enhanced RF susceptibility is found over narrow field ranges and attributed to thermally assisted driven hopping of a magnetic vortex core between neighbouring pinning sites. The on-chip magnetosusceptometer scheme offers a promising path to powerful integrated cavity optomechanical devices for the quantitative characterization of magnetic micro- and nanosystems in science and technology.
authors: Department of Physics and Astronomy and Institute for Quantum Science and Technology, University of Calgary, Calgary, Alberta T2N 1N4, Canada.|National Institute for Nanotechnology, Edmonton, Alberta T6G 2M9, Canada.
authors: Marcelo
authors: M
authors: Wu
authors: Department of Physics and Astronomy and Institute for Quantum Science and Technology, University of Calgary, Calgary, Alberta T2N 1N4, Canada.|National Institute for Nanotechnology, Edmonton, Alberta T6G 2M9, Canada.
authors: Nathanael L-Y
authors: NL
authors: Wu
authors: National Institute for Nanotechnology, Edmonton, Alberta T6G 2M9, Canada.|Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E9, Canada.
authors: Tayyaba
authors: T
authors: Firdous
authors: National Institute for Nanotechnology, Edmonton, Alberta T6G 2M9, Canada.|Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E9, Canada.
authors: Fatemeh
authors: F
authors: Fani Sani
authors: National Institute for Nanotechnology, Edmonton, Alberta T6G 2M9, Canada.|Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E9, Canada.
authors: Joseph E
authors: JE
authors: Losby
authors: National Institute for Nanotechnology, Edmonton, Alberta T6G 2M9, Canada.|Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E9, Canada.
authors: Mark R
authors: MR
authors: Freeman
authors: Department of Physics and Astronomy and Institute for Quantum Science and Technology, University of Calgary, Calgary, Alberta T2N 1N4, Canada.|National Institute for Nanotechnology, Edmonton, Alberta T6G 2M9, Canada.
authors: Paul E
authors: PE
authors: Barclay