VIBRATING SAMPLE MAGNETOMETER (VSM) MODULE

The Cryogenic VSM is a research instrument for measurements of the DC magnetic moment in fields up to 18 Tesla. Noise-floor sensitivity is 10^-6 emu with a short averaging time. The standard temperature range is 1.6K to 300K. Optionally, a sample heater is used to extend the temperature range up to 750K.

In order to generate a signal proportional to the magnetic moment, the sample is set to vibrate in a constant (or slowly varying) applied field. The signal is detected by an a static pair of pick-up coils. The coils sense the variation of magnetic flux due to the sample movement. Typical frequency of vibration is around 20 Hz, and the amplitude is 1 mm. The pick-up coils are located inside the Variable Temperature insert (VTI) within the bore of the superconducting magnet. The signal is detected by a lock-in amplifier.

Key features:
• Magnet able to operate in swept or persistent mode
• Software assisted sample change facility
• Pick-up (sense) coils located close to the samples for highest sensitivity
• Wide range of vibrator amplitude and frequencies available
• Vibrator fitted with optical and moving coil motion detector for amplitude control
• Automated sample centering and calibration procedures
• Rigid and thermally stable carbon fiber sample rod.

The magnetometer has an automated gas handling system, and the sample is loaded through an airlock. The VTI can be kept at low temperature during sample exchange, which makes the sample replacement easy and quick.

In the cryogen-free VSM special care is taken to isolate the pick-up system from vibrations generated by the cryocooler. As a consequence, the sensitivity of the cryogen-free systems is as high as in more traditional liquid helium machines. The noise floor is better than 10^-6 emu at 10 seconds integration time

The VSM can be used with a Cryogenic Limited Liquid Helium Based Magnet or a Cryogen Free Magnet.