Superfluid³He in Aerogel

Abstract

Superfluid 3 He is an unconventional neutral superfluid in a p-wave state with three different superfluid phases each identified by a unique set of characteristic broken symmetries and nontrivial topology. Despite natural immunity of 3 He from defects and impurity of any kind, it has been found that they can be artificially introduced with high porosity silica aerogel. Furthermore, it has been shown that this modified quantum liquid becomes a superfluid with remarkably sharp thermodynamic transitions from the normal state and between its various phases. They include new superfluid phases that are stabilized by anisotropy from uniform strain imposed on the silica aerogel framework and they include new phenomena in a new class of anisotropic aerogels consisting of nematically ordered alumina strands. The study of superfluid 3 He in the presence of correlated, quenched disorder from aerogel, serves as a model for understanding the effect of impurities on the symmetry and topology of unconventional superconductors.

Spin-Nernst Effect in Time-Reversal-Invariant Topological Superconductors

“…Application to candidate materials.-A wellestablished example of gapped TRI TSCs is the B-phase of superfluid 3 He. For 3 He, strong (nearunitarity) impurity scattering can be engineered by highly porous silica aerogel [60][61][62], realizing the "dirty" BW state [63][64][65][66]. The aerogel is composed of silica strands (diameter 30 Å), separated by the mean-distance that is comparable to or less than the superfluid coherence length.…”

$$^3$$He Universe 2020

“…It has topologically protected gapless Majorana fermions living on the surface. In 3 He confined in the nematically ordered aerogel, the polar phase of 3 He has been stabilized [12][13][14]. It is the time-reversal invariant superfluid, which contains Dirac nodal ring in the fermionic spectrum and flat band on the surface.…”

Signature of spin-triplet exciton condensations in LaCoO$_{3}$ at ultrahigh magnetic fields up to 600 T

“…cations in spintronics and quantum computing technologies. Condensation of spin-triplet bosons is of a fundamental interest in analogy with the spin-triplet superconductivity [20,21] and superfluidity of 3 He [22]. The condensation of spin-triplet excitons has been rarely considered in conventional studies of exciton condensations [3][4][5][6][7].…”