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()
.
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.