Vortex Core Contribution to Textural Energy in 3He–B Below 0.4T c

Abstract

Vortex lines affect the spatial order-parameter distribution in superfluid 3 He-B owing to superflow circulating around vortex cores and due to the interaction of the order parameter in the core and in the bulk as a result of superfluid coherence over the whole volume. The step-like change of the latter contribution at 0.6T c (at a pressure of 29 bar) signifies the transition from axisymmetric cores at higher temperatures to broken-symmetry cores at lower temperatures. We extended earlier measurements of the core contribution to temperatures below 0.2T c , in particular searching for a possible new core transition to lower symmetries. As a measuring tool we track the energy levels of magnon condensate states in a trap formed by the order-parameter texture.

Decay of persistent precessing domains in3He-Bat very low temperatures

“…Along the radial direction of the cylindrical cell, spin-wave modes can also form in the potential provided by the spatially varying texture as was studied in detail by Bunkov and Volovik 7 and later by Eltsov et al 23 Below, we derive expressions for spin-wave modes in three dimensions for a cylindrical cell along the vertical z axis. The cell is assumed to have a static flare-out texture in which the orbital momentum is aligned along the field direction along the cell axis, and smoothly deflects along the radial direction to be perpendicular to the vertical cell walls.…”

“…Recent experiments 17,23 clearly show that the PPD emerges from the fundamental spin-wave mode at low temperatures. However, the linear spin-wave theory given above is only applicable for small spin deflection angles, so we can only make a direct comparison to the late-time properties of the PPD, that is at the end of its decay where its amplitude tends to zero.…”

Measurements of the anisotropic mass of magnons confined in a harmonic trap in superfluid 3He-B

“…A number of effects can be observed in this system such as BoseEinstein condensation of magnons [2], Suhl instability [3] with excitation of other spin-wave modes including a longitudinal Higgs mode [4], self-localization of magnons [5]. It can be used as a probe of quantized vortices [6], Andreev bound states and gravity waves on the 3 He surface [7], boundary between 3 He-A and 3 He-B superfluids [8]. It also can be used as a tool for accurate measurements of various 3 He parameters and as a thermometer which works below 0.3 mK [8].…”

Self-Trapping of Magnon Bose-Einstein Condensates in the Ground State and on Excited Levels: From Harmonic to Box Confinement

“…Of great practical importance is the fact that these magnon condensates can be used to probe the quantum vacuum state of 3 He-B in the limit T ! 0 [10], where most conventional measuring signals become insensitive.…”