Orbital-flop transition of superfluid <sup>3</sup>He in anisotropic silica aerogel.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 38172106.
- Also identified by DOI 10.1038/s41467-023-44557-5 and PMC identifier 10764773.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Superfluid <sup>3</sup>He is a paradigm for odd-parity Cooper pairing, ranging from neutron stars to uranium-based superconducting compounds. Recently it has been shown that <sup>3</sup>He, imbibed in anisotropic silica aerogel with either positive or negative strain, preferentially selects either the chiral A-phase or the time-reversal-symmetric B-phase. This control over basic order parameter symmetry provides a useful model for understanding imperfect unconventional superconductors. For both phases, the orbital quantization axis is fixed by the direction of strain. Unexpectedly, at a specific temperature T<sub>x</sub>, the orbital axis flops by 90<sup>∘</sup>, but in reverse order for A and B-phases. Aided by diffusion limited cluster aggregation simulations of anisotropic aerogel and small angle X-ray measurements, we are able to classify these aerogels as either "planar" and "nematic" concluding that the orbital-flop is caused by competition between short and long range structures in these aerogels.