Keithley Award (2022): Pushing the Limits of Nanoscale Magnetic Resonance: From Magnetic Force Microscopy to Single Electron Spin Detection

The invention of the atomic force microscope by Binnig, Quate and Gerber[1] was a key development in nanoscience and inspired many other cantilever-based force detection modalities.   One of the most important modalities is magnetic force microscopy, which has become a standard technique widely used for the study of magnetic materials and spintronic devices. I will describe some of the early efforts in magnetic force microscopy and its evolution toward ever increasing sensitivity. A key inspiration for our work came from John Sidles (Univ. of Washington) who suggested that force detection techniques might be applied to magnetic resonance detection and possibly achieve three-dimensional imaging of molecules[2]. Motivated by this possibility, our group at IBM-Almaden pushed the sensitivity of cantilever-based force detection to the attonewton level, allowing the detection of a single electron spin and, later, nanoscale nuclear spin imaging. This talk will give a personal perspective of this research journey. Various innovations developed along the way will be highlighted, as well as some of the remaining challenges.

[1] G. Binnig, C. F. Quate, and Ch. Gerber, "Atomic Force Microscope", Phys. Rev. Lett. 56, 930 (1986).

[2] J. A. Sidles, "Folded Stern-Gerlach experiment as a means for detecting nuclear magnetic resonance in individual nuclei", Phys. Rev. Lett. 68, 1124 (1992).