Development of High-Sensitivity Cantilever-Detected ESR Measurement Using a Fiber-Optic Interferometer

  • Tokuda, Yuki (Graduate School of Science, Kobe University) ;
  • Tsubokura, Daichi (Graduate School of Science, Kobe University) ;
  • Ohmichi, Eiji (Graduate School of Science, Kobe University) ;
  • Ohta, Hitoshi (Molecular Photoscience Research Center, Kobe University)
  • Received : 2012.05.31
  • Accepted : 2012.08.09
  • Published : 2013.06.30


Cantilever-detected high-frequency electron spin resonance (ESR) is a powerful method of sub-terahertz and terahertz ESR spectroscopy for a tiny magnetic sample at low temperature. In this technique, a small magnetization change associated with ESR transition is detected as deflection of a sample-mounted cantilever. So far, we have succeeded in ESR detection at 370 GHz using a commercial piezoresistive microcantilever. The spin sensitivity was estimated to ${\sim}10^{12}$ spins/gauss. In order to further increase the sensitivity, we adopt a fiber-optic-based detection system using a Fabry-Perot interferometer in place of piezoresistive system. Fabry-Perot cavity is formed between an optical-fiber end and microcantilever surface, and a change in the interference signal, corresponding to the cantilever deflection, is sensitively detected. This system is suitable for low-temperature and high-magnetic-field experiments because of its compact setup and less heat dissipation. In this study, performance of Fabry-Perot interferometer is evaluated, and its application to cantilever-detected ESR measurement is described.


electron spin resonance;microcantilever;fabry-perot interferometer;terahertz wave


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