Raffi Budakian, University of Illinois at Urbana-Champaign
Abstract
Since the invention of the atomic force microscope (AFM) by Binnig, Quate and Gerber in 1986, force-based scanning probes have become an essential tool for imaging, manipulating and measuring materials on the nanometer scale. At the heart of the AFM is a mechanical sensor or cantilever that transduces the force generated between the probe tip and the sample into a displacement.
In most applications, an AFM is used to probe molecular interactions in the 10-9 N-10-12 N range. However, advances in nanofabrication, high precision displacement detection, and low temperature measurement are opening up new areas of research that use cantilevers for ultrahigh precision metrology, as well as to investigate fundamental issues in quantum mechanics. In this talk, I will present two projects being pursued in my group that use cantileverbased force detection to investigate magnetic phenomena on the nanometer scale. In the first part of my talk, I will discuss ongoing experiments that use self-assembled nanowire mechanical resonators that achieve sub-attonewton (10-18 N) force sensitivity to perform nanometer-scale nuclear magnetic resonance imaging. In the second half of the talk, I will present cantilever magnetometry measurements that show the existence of half-integer fluxoid states in mesoscopic annuli fabricated from the superconductor Sr2RuO4. These fractional vortex states may be the first experimental observation of half-quantum vortices predicted to exist in the equal spin pairing state of spin-triplet superfluids. I will conclude by discussing recent experimental studies of the current- phase relationship of weak-link Josephson junctions fabricated in Sr2RuO4 annuli.