Superfluid Helium-3 in Aerogel in the Absence of Magnetic Scattering*

Confining superfluid helium-3 in a porous aerogel both suppresses and alters the relative stabilities of the superfluid. Moreover, the presence of disorder and anisotropy in the imbibed superfluid helium-3 system can work to alter the orientation of the order parameter, supporting well-resolved order parameter orientation transitions and superfluid glass phases[1,2]. We report results of ongoing pulsed NMR studies over a range of fields 0.05T-0.2T of superfluid helium-3 imbibed in isotropic and both 7% and 12% radially shrunken aerogels, with magnetic impurity scattering channels suppressed by a coating of solid helium-4 on the surface of the aerogel[3]. Prior experiments in radially shrunken aerogels observed the total suppression of non-equal spin pairing phases of helium-3 and, likewise, previous experiments in homogeneous aerogels have exhibited superfluid glass phases of helium-3, with both 2-dimensional and 3-dimensional disordered phases observed depending on the phase from which the superfluid glass is nucleated[4,1].

1. Li et al. Nat. Phys. 9, 775-779 (2013).

2. Zimmerman et al. Phys. Rev. Lett. 121, 255303 (2018).

3. Zimmerman et al. Phys. Rev. Lett. 124, 025302 (2020).

4. Pollanen et al. Nat. Phys. 8, 317-320 (2012).