NMR Time Reversal Experiments in Highly Polarised Liquid 3He-4He Mixtures

Abstract

Long-range magnetic interactions in highly magnetised liquids (laser-polarised 3 He-4 He dilute mixtures at 1 K in our experiment) introduce a significant non-linear and non-local contribution to the evolution of nuclear magnetisation that leads to instabilities during free precession. We recently demonstrated that a multi-echo NMR sequence, based on the magic sandwich pulse scheme developed for solid-state NMR, can be used to stabilise the magnetisation against the effect of distant dipolar fields. Here, we report investigations of echo attenuation in an applied field gradient that show the potential of this NMR sequence for spin diffusion measurements at high magnetisation densities.

Optically polarizedHe3

“…III.B.2), but room temperature OP with polarized gas transfer enabled a series of low-temperature studies of 3 He as a quantum fluid: characterization of spin waves (Nacher et al , 1984; Tastevin et al , 1985) and heat conduction changes (Larat et al , 1990; Leduc et al , 1987) in 3 He gas and of phase coexistence for liquid 3 He (Candela et al , 1994; Tastevin, 1992b; Villard et al , 2000). A similar technique was used with refillable cells to repeatedly prepare larger samples of polarized liquid in which magnetic interactions play a key role in non-linear NMR dynamics (Baudin et al , 2008; Hayden et al , 2007). …”

“…The macroscopic behavior of spin-polarized 3 He fluids is modified at low temperature by polarization of the 3 He nuclei (Castaing and Nozieres, 1979; Lhuillier and Laloë, 1979, 1982; Owers-Bradley, 1997). Nonlinear spin dynamics (Akimoto et al , 2000; Desvaux, 2013), and NMR time reversal (Baudin et al , 2008) have been studied in 3 He- 4 He mixtures.…”

Optically Polarized $^3$He

“…The macroscopic behavior of spin-polarized 3 He fluids is modified at low temperature by polarization of the 3 He nuclei (Castaing and Nozieres, 1979;Laloë, 1979, 1982;Owers-Bradley, 1997). Nonlinear spin dynamics (Akimoto et al, 2000;Desvaux, 2013), and NMR time reversal (Baudin et al, 2008) have been studied in 3 He-4 He mixtures.…”