Fig. 1
The experimental setup and superfluid phase diagram in nanoconfinement. a The 3He sample is confined within a cylindrical container filled with commercially available nanomaterial called nafen-90 (where the number refers to its density in mg cm−3) with uniaxial anisotropy, which consists of nearly parallel Al2O3 strands with d2 ≈ 8 nm diameter, separated by d1 ≈ 50 nm on average. The strands are oriented predominantly along the axis denoted as \({\hat{\mathbf z}}\). The sample can be rotated with angular velocities up to 3 rad s−1 around the same axis \({\hat{\mathbf z}}\). The sample is surrounded by rectangular nuclear magnetic resonance (NMR) pick-up coils. The static magnetic field transverse to the NMR coils can be oriented at an arbitrary angle μ with respect to the \({\hat{\mathbf z}}\) axis. b The magnetic field, oriented along the y-direction (μ = π/2) in this figure, locks the \({\hat{\mathbf e}}^2\)-vector in the polar-distorted B phase order parameter, Eq. (4). Vectors \({\hat{\mathbf d}}\) and \({\hat{\mathbf e}}^1\) are free to rotate in the xz-plane by angle θ. c Sketch of the superfluid phase diagram in our sample in units of Tc of the bulk fluid31. The purple arrows illustrate the thermal cycling used in the measurements and the purple marker shows a typical measurement point within the region where either polar-distorted phase can exist, depending on the direction of the temperature sweep. The thermal cycling is performed at constant 7 bar pressure
