van der Sar, ToenoCasola, FrancescoWalsworth, RonaldYacoby, Amir2017-02-212015Van der Sar, Toeno, Francesco Casola, Ronald Walsworth, and Amir Yacoby. 2015. Nanometre-Scale Probing of Spin Waves Using Single-Electron Spins. Nat Comms 6: 7886. doi:10.1038/ncomms8886.2041-1723http://nrs.harvard.edu/urn-3:HUL.InstRepos:30403686Pushing the frontiers of condensed-matter magnetism requires the development of tools that provide real-space, few-nanometre-scale probing of correlated-electron magnetic excitations under ambient conditions. Here we present a practical approach to meet this challenge, using magnetometry based on single nitrogen-vacancy centres in diamond. We focus on spin-wave excitations in a ferromagnetic microdisc, and demonstrate local, quantitative and phase-sensitive detection of the spin-wave magnetic field at ~50 nm from the disc. We map the magnetic-field dependence of spin-wave excitations by detecting the associated local reduction in the disc’s longitudinal magnetization. In addition, we characterize the spin–noise spectrum by nitrogen-vacancy spin relaxometry, finding excellent agreement with a general analytical description of the stray fields produced by spin–spin correlations in a 2D magnetic system. These complementary measurement modalities pave the way towards imaging the local excitations of systems such as ferromagnets and antiferromagnets, skyrmions, atomically assembled quantum magnets, and spin ice.en-USphysical sciencesapplied physicsnanotechnologyJournal Article2017-02-2110.1038/ncomms8886