Direct observation of local magnetic field generated by micromagnet

Using standard nuclear magnetic resonance (NMR) technique and a well-fabricated sample, we have succeeded in directly observing local magnetic field generated by a micromagnet Ni 45 Fe 55 (with thickness of 400 nm ), which was sputtered on an Al layer of 20 nm thickness. Improved sensitivity of our NMR technique enabled us to clearly observe Al-NMR signals, which are confirmed to come from Al nuclei in the 20 nm layers. From the analysis of the Al-NMR spectra, the local magnetic field was found to be + 0.17 ± 0.02 ( − 0.20 ± 0.01 ) T , the sign of which is consistent with the geometry that the external magnetic field was applied perpendicular (parallel) to the Al layer. The present study gives a potential key element toward realizing higher resolution in magnetic resonance imaging.