GOALI: Advanced Cantilevers for MRFM with IBM Almaden

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An important new imaging technique has been proposed by Sidles, in which forces derived from a Nuclear Magnetic Resonance (NMR) measurement would be measured accurately enough to allow 3-dimensional imaging of individual atoms. Electronic nanodevice evaluation, gene sequenceing, drug development, ananlysis of storage media, and many other commerical, medical and industrial applicatons would would benefit from this new imaging technology. The basic challenge of Magnetic Resonance Force Microscopy (MRFM) lies in the exceedingly small forces which must be detected, which are of order atto-newtons (1 aN=10-18N). Force detection sensitivity of mechanical cantilevers is ultimately limited by thermo-mechanical noise which apprears as a force fluctuation. To achieve the very high sensitivity required for MRFM, the temperature and stiffness of the cantilever must be minimized while maximizing Q. Research to obtain sngle-atom imaging by MRFM has been underway in Rugar's IBM Almaden group for several years, and significant progress has occurred. Recent research has included demonstrations of the ability to detect atto-newton forces, observation of numerous fN-sale forces near surfaces, and work to identify and reduce the mechanism for thermo-mechanical noise inthe cantilevers used to detect these forces. all of this has taken place during a GOALI-Funded collaboration between Standford and IBM, which has featured student research at IBM and use of NNUN facilities at Stanford to fabricate unique cantilevers. Our goals in this renewal effort focus on cntinued work to understand and reduce the damping mechanism in micromechanical cantilevers that limit the value of Q. We have constructed an apparatus which allows systematic experimental measurements of cantilever Q as a function of temperature, dimensions, and materials, and we will use this to identify damping mechanisms. Also we propose to develop a new design for a micromechanical cantilever that will allow in-situ annealing in the MRFM apparatus. In addition, we have used these sentisitve cantilevers to develop develop a novel surface dissipation microscopy, in which trapped charges on the cantilever induce surface charges whose mobility can be determined on the nm-scale. Work along all 3 of these directions will continue. The long-term goal remains the demonstration of MRFM imaging of sigle atoms.