attoAFM/CFM with Free-Beam Optics for NV Magnetometry

in top-loading dilution refrigerator

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  1. Leiden Cryogenics dry DR
  2. top-loading insert
  3. attoCFM I external optics head for free-beam confocal microscopy
  4. vector magnet
  5. attoAFM/CFM microscope moduel for mK
  6. cryogenic objective
  7. AFM with the Akiyama probe
  8. sample

mK-AFM_CFM-for-NV-Magnetometry.svg

In close collaboration with Leiden Cryogenics and the Quantum Sensing group of Patrick Maletinsky (University of Basel, Switzerland), we have developed a complete mK AFM/CFM based on a closed-cycle top-loading DR. The system is used for quantum sensing and imaging at mK temperatures. The toploading probe minimizes the turnaround time upon tip or sample exchange to only ~8 hours instead of 24-48 hours for warming up the whole DR. Long turnaround time can quickly become a prohibitive shortcoming for efficient SPM measurements.

The combined AFM/CFM features a free-beam confocal microscope, with the attoCFM I external optics head sitting on top of the top-loading insert. Despite long distance to the magnetic field center where the sample is mounted, attoAFM/CFM allows for the full range of confocal applications with all the flexibility of having several optical channels featuring easy alignment and very high long-term stability. The microscope module itself has been completely redesigned for the mK environment, as well as carefully thermalized and wired. In this configuration, a base temperature of 38 mK at the sample location has been achieved.