Application of low frequency SQUID NMR to the ultra-low temperature study of atomically layered 3He films adsorbed on graphite

Low frequency pulsed NMR is a powerful technique for the investigation of the nuclear susceptibility and spin-dynamics of strongly correlated systems down to ultra-low temperatures. We describe a versatile broadband pulsed NMR spectrometer using a two- stage Superconducting Quantum Interference Devi...

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Bibliographic Details
Published in:Journal of physics. Conference series 2014-12, Vol.568 (3)
Main Authors: Arnold, F, Nyéki, J, Casey, A J, Shibahara, A, Cowan, B P
Format: Article
Language:English
Subjects:
Broadband
Ferromagnetism
Fluid films
Graphite
Low frequencies
Low temperature
NMR
Nuclear magnetic resonance
Physics
Spin dynamics
Spin-lattice relaxation
Superconducting quantum interference devices
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Summary:Low frequency pulsed NMR is a powerful technique for the investigation of the nuclear susceptibility and spin-dynamics of strongly correlated systems down to ultra-low temperatures. We describe a versatile broadband pulsed NMR spectrometer using a two- stage Superconducting Quantum Interference Device (SQUID). This instrument has enabled the investigation of the spin-dynamics of 3He films adsorbed on exfoliated graphite into the microkelvin temperature range. In prior work we reported a SQUID NMR study of twodimensional ferromagnetism on a triangular lattice, where 3He films adsorbed on graphite provide an ideal model system. Here we describe the detection of the much weaker signals from strongly correlated fluid films in the second layer of 3He on graphite, using a spectrometer with improved sensitivity. We have measured the low frequency spin-spin relaxation and spin-lattice relaxation of two-dimensional 3He into the microkelvin range. These show an unusual time and frequency dependence. We also describe the use of the 13C-signal from the exfoliated graphite for thermometry, and the unusual properties of the spin-lattice relaxation of that system.
ISSN:1742-6588
1742-6596
DOI:10.1088/1742-6596/568/3/032020