title: Relaxometry and Dephasing Imaging of Superparamagnetic Magnetite Nanoparticles Using a Single Qubit.
abstract: To study the magnetic dynamics of superparamagnetic nanoparticles, we use scanning probe relaxometry and dephasing of the nitrogen vacancy (NV) center in diamond, characterizing the spin noise of a single 10 nm magnetite particle. Additionally, we show the anisotropy of the NV sensitivity's dependence on the applied decoherence measurement method. By comparing the change in relaxation (T1) and dephasing (T2) time in the NV center when scanning a nanoparticle over it, we are able to extract the nanoparticle's diameter and distance from the NV center using an Ornstein-Uhlenbeck model for the nanoparticle's fluctuations. This scanning probe technique can be used in the future to characterize different spin label substitutes for both medical applications and basic magnetic nanoparticle behavior.
authors.forename: Dominik
authors.initials: D
authors.lastname: Schmid-Lorch
authors.forename: Thomas
authors.initials: T
authors.lastname: Häberle
authors.forename: Friedemann
authors.initials: F
authors.lastname: Reinhard
authors.forename: Andrea
authors.initials: A
authors.lastname: Zappe
authors.forename: Michael
authors.initials: M
authors.lastname: Slota
authors.affiliation: §Department of Materials, University of Oxford, 16 Parks Road, OX1 3PH, Oxford, United Kingdom.
authors.forename: Lapo
authors.initials: L
authors.lastname: Bogani
authors.forename: Amit
authors.initials: A
authors.lastname: Finkler
authors.affiliation: ∥Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Wrachtrup
keywords: Superparamagnetism; T1 relaxation time; T2 dephasing time; scanning probe microscopy,; shallow nitrogen vacancy center