Specialized Instruments

Cells, resonators, amplifiers and other instruments are available to use in conjunction with a variety of measurements.

High-Frequency NMR

Pulsed NMR spectrometers capable of operating up tp 1600 MHz are available for studies at very low temperatures. The probes used are usually specifically designed for a given experimental situation.

This probe system was used successfully to study quantum diffusion of 3He in superfluid 4He using NMR techniques (H. Akimoto et al. Phys. Rev. Lett. 99, 095301 (2007).

This technique can be used with:

For more information, please contact Neil Sullivan.

Low-temperature Electronics

Pseudomorphic high mobility field effect transistors are used to provide power matching at moderately high frequencies (up to 2MHz) . The deployment of these for low-temperature matching of high Q NMR signals (at low frequencies) is critical for maximizing signal/noise ratios for challenging samples. The circuit can operate down to 0.4 mK as limited by its internal power dissipation but can be maintained in close proximity to a receiving coil and allowed to rise in temperature independent of the sample.

A simple source follower circuit is used with the active element oriented parallel to the applied magnetic field. Precise impedance matching can be achieved by adjusting the gate voltage via an external lead. Show below are (a) the circuit diagram, and (b) a picture showing the physical positioning of the amplifier in close proximity to an NMR probe. For details see: C. Huan et al. J. Low Temp. Phys. 158, 692 (2010).

This technique can be used with:

For more information, please contact Neil Sullivan.

Ultra Low-temperature Rotator

The driving piece of the rotator is a BeCu bellows filled with pressurized liquid 3He. The vertical motion is transmitted to a T-shaped joint which causes the sample platform to rotate.

This technique can be used with:

For more information, please contact Jian-Sheng Xia.

Last modified on 8 October 2014