Browsing by Author "Salmelin, R. H."

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Coupling of zero sound to the real squashing mode in rotating 3He-B
(1989-08-07) Salmelin, R. H.; Pekola, J. P.; Manninen, A. J.; Torizuka, K.; Berglund, M. P.; Kyynäräinen, J. M.; Lounasmaa, O. V.; Tvalashvili, G. K.; Magradze, O. V.; Varoquaux, E.; Avenel, O.; Mineev, V. P.
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Rotation of superfluid B3 in an magnetic field enhances the coupling of the nonzero mJ substrates of the real squashing collective mode to the zero sound, and the fivefold line splitting becomes observable even when H is parallel to and to the direction of sound propagation. Equilibrium vortex lattices and vortex-free states can be distinguished by their characteristic absorption spectra. The dependence of the sound attenuation on the angular velocity in magnetic fields up to 32 mT is reported; the data are qualitatively compared with theory.
Internal magnus effects in superfluid 3He-A
(1989-08) Salmelin, R. H.; Salomaa, M. M.; Mineev, V. P.
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Orbital angular momentum of the coherently aligned Cooper pairs in superfluid A3 is encountered by an object immersed in the condensate. We evaluate the associated quasiparticle-scattering asymmetry experienced by a negative ion; this leads to a measureable, purely quantum-mechanical reactive force deflecting the ions trajectory. Possible hydrodynamic Magnus effects are also discussed.
Resonant quasiparticle-ion scattering in anisotropic superfluid 3He
(1990-03) Salmelin, R. H.; Salomaa, M. M.
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Low-energy excitations in quantum fluids are most directly encountered by ions. In the superfluid phases of He3 the relevant elementary excitations are Bogoliubov quasiparticles, which undergo repeated scattering off an ion in the presence of a divergent density of states. We present a quantum-mechanical calculation of the resonant He3 quasiparticle-scattering-limited mobility for negative ions in the anisotropic bulk A3 (A phase) and P3 (polar phase) that is exact when the quasiparticles scatter elastically. We develop a numerical scheme to solve the singular equations for quasiparticle-ion scattering in the A and P phases. Both of these superfluid phases feature a uniaxially symmetric order parameter but distinct topology for the magnitude of the energy gap on the Fermi sphere, i.e., points versus lines of nodes. In particular, the perpetual orbital circulation of Cooper pairs in A3 results in a novel, purely quantum mechanical intrinsic Magnus effect, which is absent in the polar phase, where Cooper pairs possess no spontaneous orbital angular momentum. This is of interest also for transport properties of heavy-fermion superconductors. We discuss the He3 quasiparticle-ion cross sections, which allow one to account for the mobility data with essentially no free parameters. The calculated mobility thus facilitates an introduction of ion spectroscopy to extract useful information on fundamental properties of the superfluid state, such as the temperature dependence of the energy gap in A3.