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arXiv · 1605.03138

Nanocavity optomechanical torque magnetometry and radiofrequency susceptometry

Marcelo Wu·Nathanael L. -Y. Wu·Tayyaba Firdous·Fatemeh Fani Sani·Joseph E. Losby·Mark R. Freeman·Paul E. Barclay
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Abstract

Nanophotonic optomechanical devices allow observation of nanoscale vibrations with sensitivity that has dramatically advanced metrology of nanomechanical structures [1-9] and has the potential to impact studies of nanoscale physical systems in a similar manner [10, 11]. 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 observation of Barkhausen steps in the magnetic hysteresis of a lithographically patterned permalloy island [12]. 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 neighboring pinning sites [13]. The on-chip magneto-susceptometer scheme offers a promising path to powerful integrated cavity optomechanical devices for quantitative characterization of magnetic micro- and nanosystems in science and technology.

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Marcelo Wu, Nathanael L. -Y. Wu, Tayyaba Firdous, Fatemeh Fani Sani, Joseph E. Losby, Mark R. Freeman, Paul E. Barclay. 2016-11-02. Nanocavity optomechanical torque magnetometry and radiofrequency susceptometry. https://doi.org/10.1038/nnano.2016.226

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