Abstract
Both the length scale and the magnetic field strength dependence of the magnetic noise in ac magnetically driven garnets were measured optically using the Faraday effect. At fields in a limited region, roughly twice the coercive field, the noise exhibits a Lorentzian power spectral density (PSD) consistent with random telegraph noise (RTN). The RTN onset as a function of applied field is rather abrupt and then decreases slowly with further increases in the applied field. The PSD of the noise in the lowest and highest magnetic field regimes is white background noise and is about two decades smaller than that of the RTN. In the field regime of the RTN, the PSD is Lorentzian at all measured length scales. As the measurement length scale increases past the order of a few microns, the low-frequency plateau of the Lorentzian PSD diminishes with increasing area measured as expected for a collection of uncorrelated RTN oscillators with similar characteristic frequencies.
Original language | English (US) |
---|---|
Article number | 134411 |
Journal | Physical Review B |
Volume | 103 |
Issue number | 13 |
DOIs | |
State | Published - Apr 8 2021 |
Bibliographical note
Funding Information:The authors thank Devlin Gualtieri (Allied Signal Corporation, Morristown, NJ) for many of the samples used in this investigation, and Michael Weissman for an interesting conversation. We also thank Maarten Rutgers and Jason Cleveland for preliminary studies of the noise in magnetic field driven garnets. This work was supported primarily by NSF Grant No. DMR 1609782.
Publisher Copyright:
© 2021 American Physical Society.