While Magnetic Resonance Force Microscopy is capable of imaging three dimensional structures on nanoscopic scales, the number of practical applications so far has been limited, partly due to the...Show moreWhile Magnetic Resonance Force Microscopy is capable of imaging three dimensional structures on nanoscopic scales, the number of practical applications so far has been limited, partly due to the complexity of the device. In this thesis we introduce the Easy MRFM, a way to increase the usability of MRFM. By seperating all MRFM components from the sample, we hope to remove some of the drawbacks of the previous Oosterkamp MRFM, allowing for easier data analysis and sample exchange. This thesis provides the theoretical calculations for the optimal set-up of the Easy MRFM and a preliminary proof of concept. Furthermore it describes a new way to analyse the measurements of the cantilever properties which would be better suited for the Easy MRFM. It also It includes the characterization of a new cantilever which could possibly be used inside the Easy MRFM to increase its sensitivity.Show less
In this thesis we describe the potential application of Si3N4 cantilevers in a Magnetic Resonance Force Microscopy (MRFM) setup. In a characterization of these cantilevers we find quality factors...Show moreIn this thesis we describe the potential application of Si3N4 cantilevers in a Magnetic Resonance Force Microscopy (MRFM) setup. In a characterization of these cantilevers we find quality factors up to 26000 at 100 mK and determine the thermal force noise SF to be 0.66 aN/√(Hz), which is competitive with currently used single crystal silicon cantilevers. With this we show that Si3N4 cantilevers are suitable replacements for the currently used MRFM cantilevers. We perform a study of the higher order resonance modes of this cantilever and compare this to a simulation of the eigenfrequencies of the cantilever. Lastly we describe a method of applying feedback with a specific phase or gain to the cantilever. We use this feedback to cool the effective temperature of the fundamental resonance mode of the cantilever from a saturation temperature of 100 mK to 28 mK. We show that this result is limited by the high detection noise in the setup and make suggestions for further improvements. This new, more convenient, feedback scheme should allow for easier implementation of feedback cooling in future MRFM experiments.Show less
We have investigated the technical feasibility of a novel concept within the scientific field of magnetic resonance force microscopy (MRFM), in which a cantilever is used as a force sensor on the...Show moreWe have investigated the technical feasibility of a novel concept within the scientific field of magnetic resonance force microscopy (MRFM), in which a cantilever is used as a force sensor on the one hand and a radio frequency (rf) source on the other. By driving a magnet-tipped cantilever at a higher resonance mode, the rotational motion of the magnetic tip generates an oscillating magnetic field. In this way the cantilever can serve as an ultra-low dissipative rf source with an rf frequency corresponding to the specific higher mechanical resonance mode of the cantilever. In this work we have tested this idea for an attonewton-sensitivity silicon cantilever with a high magnetic gradient cobalt nanomagnet attached at the cantilever's free end. Using frequency-shift cantilever magnetometry, we found that the nanomagnet's remanent magnetisation is 0.83 tesla. When the nanomagnet is close enough to a spin-containing sample, we have calculated that the nanomagnet's magnetisation - even at zero applied magnetic field - can mechanically generate an rf field of the order millitesla. This implies that the protocol for adiabatic rapid passage can be conducted without the use of an rf wire as a radio frequency source, which eliminates a major dissipation channel that constitutes an obstacle to date for lower working temperatures in high resolution 3D-imaging experiments with MRFM.Show less
