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

27th International Conference on Low Temperature Physics

Arnold, F.^1 ; Yager, B.^1 ; Nyéki, J.^1 ; Casey, A.J.^1 ; Shibahara, A.^1 ; Cowan, B.P.^1 ; Saunders, J.^1

Royal Holloway, University of London, Egham

TW20 0EX, United Kingdom^1

关键词: Correlated fluids;    Exfoliated graphite;    Nuclear susceptibility;    Spin-spin relaxation;    Strongly correlated systems;    Time and frequencies;    Triangular lattice;    Ultra low temperatures;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/568/3/032020/pdf
DOI  :  10.1088/1742-6596/568/3/032020

来源: IOP

【 摘 要 】

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 of3He 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, where3He 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 of3He on graphite, using a spectrometer with improved sensitivity. We have measured the low frequency spin-spin relaxation and spin-lattice relaxation of two-dimensional3He into the microkelvin range. These show an unusual time and frequency dependence. We also describe the use of the13C-signal from the exfoliated graphite for thermometry, and the unusual properties of the spin-lattice relaxation of that system.