Before pulsed field measurements can be taken, a sample must be prepared and attached to the probe. This process includes the placement of leads that will carry the signal from the sample. Further, the sample must be securely connected to the probe so that it does not move during the magnetic field pulse.
appropriate leads must be attached to your sample depending on what type
of measurements will be taken. For most experiments, attach four leads to
the sample: two to carry the current and two to measure the voltage. If
desired, two additional leads can be added to measure Hall resistance, making
a total of six leads. It is common to use 1 mil gold wire to construct leads,
however many other types are acceptable. These leads are attached with a
variety of things, including epoxy and gold, graphite or silver paste, depending
on the sample.
Once leads are in place, the sample can be placed on a 2 mm x 2 mm x .5 mm (approximately) piece of sapphire. Sapphire is used because it has high conductivity, but is also well insulated. Some glue is necessary to hold the sample in place such as GE varnish or Duco cement.
Finally, the sample is attached to the probe using a variety of methods. Some samples are first placed in a removable socket to hold the sample in place on the probe while other samples can be placed directly on the probe.
GENERAL MAGNETIZATION MEASUREMENTS:
For investigations involving the de Haas-van Alphen Effect, the sample is placed directly inside the pick-up coils (without leads attached), or occasionally on the end of the coils. In order to fit inside the coils (whereupon the best signal-to-noise is obtained), the sample must be able to fit inside a hole with a diameter of 400 microns (2-3 mm long). Small amounts of silicon-based vacuum grease are used to prevent the sample from moving during the pulse.
In the case of magnetization
measurements, it is important for the sample to be moved in and out of
the coils (in-situ) between pulses. For this reason, the pick-up coils
are made larger in order to accommodate a capsule that contains the sample.
The internal diameter of the capsule is approximately 900 microns (2 mm