TY - JOUR
T1 - Chiral superfluid helium-3 in the quasi-two-dimensional limit
AU - Heikkinen, Petri
AU - Levitin, Lev
AU - Rojas, Xavier
AU - Singh, Angadjit
AU - Eng, Nathan
AU - Casey, Andrew
AU - Saunders, John
AU - Vorontsov, Anton
AU - Zhelev, Nikolay
AU - Sebastian, Abhlash Thanniyil
AU - Parpia, Jeevak
PY - 2025/3/31
Y1 - 2025/3/31
N2 - Anisotropic pair breaking close to surfaces favors the chiral 𝐴 phase of the superfluid 3He over the time-reversal invariant 𝐵 phase. Confining the superfluid 3He into a cavity of height 𝐷 of the order of the Cooper pair size characterized by the coherence length 𝜉0—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 4He 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/𝜉0 =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 𝑝𝑥 +𝑖𝑝𝑦 superfluid under more extreme confinement.
AB - Anisotropic pair breaking close to surfaces favors the chiral 𝐴 phase of the superfluid 3He over the time-reversal invariant 𝐵 phase. Confining the superfluid 3He into a cavity of height 𝐷 of the order of the Cooper pair size characterized by the coherence length 𝜉0—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 4He 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/𝜉0 =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 𝑝𝑥 +𝑖𝑝𝑦 superfluid under more extreme confinement.
UR - https://doi.org/10.48550/arXiv.2409.12901
U2 - 10.1103/PhysRevLett.134.136001
DO - 10.1103/PhysRevLett.134.136001
M3 - Article
SN - 1079-7114
VL - 134
JO - Physical Review Letters
JF - Physical Review Letters
IS - 13
M1 - 136001
ER -