Kavli Affiliate: Jeevak M. Parpia
| First 5 Authors: Petri J. Heikkinen, Lev V. Levitin, Xavier Rojas, Angadjit Singh, Nathan Eng
| Summary:
Anisotropic pair breaking close to surfaces favors the chiral A phase of the
superfluid $^3$He over the time-reversal invariant B phase. Confining the
superfluid $^3$He into a cavity of height $D$ of the order of the Cooper pair
size characterized by the coherence length $xi_0$ – ranging between 16 nm (34
bar) and 77 nm (0 bar) – extends the surface effects over the whole sample
volume, thus allowing stabilization of the A phase at pressures $P$ and
temperatures $T$ where otherwise the B phase would be stable. In this Letter,
the surfaces of such a confined sample are covered with a superfluid $^4$He
film to create specular quasiparticle scattering boundary conditions,
preventing the suppression of the superfluid order parameter. We show that the
chiral A phase is the stable superfluid phase under strong confinement over the
full $P$-$T$ phase diagram down to a quasi-two-dimensional limit $D / xi_0 =
1$ , where $D = 80$ nm. The planar phase, which is degenerate with the chiral A
phase in the weak-coupling limit, is not observed. The gap inferred from
measurements over the wide pressure range from 0.2 to 21.0 bar leads to an
empirical ansatz for temperature-dependent strong-coupling effects. We discuss
how these results pave the way for the realization of the fully gapped
two-dimensional $p_x + ip_y$ superfluid under more extreme confinement.
| Search Query: ArXiv Query: search_query=au:”Jeevak M. Parpia”&id_list=&start=0&max_results=3