Characterization of silicon nitride cantilevers and mechanical feedback cooling

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Characterization of silicon nitride cantilevers and mechanical feedback cooling

Type: Master thesis
Title: Characterization of silicon nitride cantilevers and mechanical feedback cooling
Author: Opdam, Daniel
Issue Date: 2018
Keywords: MRFM
cantilever
Scanning probe microscope
feedback cooling
mechanical cooling
low temperature
Abstract: 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 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.
Supervisor: Oosterkamp, Tjerk
Faculty: Faculty of Science
Department: Physics (Master)
Specialisation: Quantum matter and optics
ECTS Credits: 3
Handle: http://hdl.handle.net/1887/63098
 

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