Typical Workflow

Preliminary Steps

• Align SQUID at room temperature.

• Move the SQUID vertically far from the sample using the Attocubes.

• Cool down your fridge.

• Test and tune the SQUID once it is cold.

• Measure and record the scanner and Attocube capacitances.

• Check the cantilever capacitance.

• Create a directory on the data acquisition computer to hold all of the data and documentation for the cooldown.

• In this directory, create Microscope Configuration and Measurement Configuration JSON files, then launch a Jupyter Notebook.

• In the Notebook, import any modules you’ll need during the cooldown and add the scanning-squid repository to your path.

Initialize the Microscope

• Initialize the microscope from the Microscope Configuration file.

• If something goes wrong, you can always restart the Jupyter Notebook kernel and/or re-initialize the microscope.

Load the Measurement Configuration

• Load the Measurement Configuration file using utils.load_json_ordered().

• When you make changes to this file, be sure to re-load it.

Approach the Sample

• See: Approaching the Sample.

  Note

  If the initial touchdown occurs at negative z scanner voltage, consider using the Attocubes to move such that touchdown occurs at a positive voltage. This way, if something goes wrong and the DAQ analog outputs go to 0 V, the SQUID will not be slammed into the sample.

  Warning

  This is the most dangerous/uncertain part of most measurements. If the capacitance is very noisy or the cantilever is not well-constructed, you risk not detecting the touchdown and crashing the SQUID into the sample using the Attocubes.

Acquire a Surface

• See: Acquiring a Surface

Scan Over the Plane

• Define your scan parameters in the Measurement Configuration then reload the file using utils.load_json_ordered().

• Start Scanning, sit back, and enjoy the ScanPlot!

Move Around the Sample

• Use the instruments.atto.AttocubeController to move around the sample, keeping in mind the angle between SQUID and sample so as not to accidentally crash.

• Unless the sample is very flat, it will be necessary to acquire a new plane after moving the Attocubes.

• If the sample is very flat and you still trust the old plane after moving the Attocubes, you can perform a single Capacitive touchdown at the origin and manually set atto.surface_is_current = True to update the plane.