Dissipation in superfluid ³He weak links

We study the dissipative currents in ³He weak links subjected to pressure biases. Recent experiments on the dc currents through an array-type weak link were only analyzed by phenomenological models [1]. We show that the order of magnitude of these currents may be accounted for by the well-known process of "multiple Andreev reflections" [2], where the number of Andreev reflections is limited by inelastic processes due to quasiparticle-quasiparticle collisions. In this case the current-pressure (I-P) characteristics should be strictly linear and independent of textural configurations in the low-pressure regime (see figure). However, the observed I-P curves were strongly nonlinear and different for the "H" and "L" states which have previously been interpreted as two different textural states [3,4]. We show that at least part of these deviations can be explained by the anisotextural effect [3,4], which was used to explain the existence of the "π states" in the same experimental setup.

1. R. W. Simmonds, A. Marchenkov, S. Vitale, J. C. Davis, and R. E. Packard, Phys. Rev. Lett. 84, 6062 (2000).
2. See for example D. V. Averin, cond-mat/9803065.
3. J.K. Viljas and E.V. Thuneberg, Phys. Rev. Lett. 83, 3868 (1999), cond-mat 9907181.
4. J.K. Viljas and E.V. Thuneberg, Phys. Rev. B 65, 64530 (2002), cond-mat 0107052.

Publications

• J. K. Viljas and E. V. Thuneberg, Dissipative Currents in Superfluid ³He Weak Links, Phys. Rev. Lett. 93, 205301 (2004), cond-mat/0401637.
• J. K. Viljas and E. V. Thuneberg, Dissipative Currents in Superfluid ³He-B Weak Links, J. Low Temp. Phys. 134, 743 (2004), preprint.
• J. K. Viljas and E. V. Thuneberg, Textural Effects and Spin-wave Radiation in Superfluid ³He Weak Links, J. Low Temp. Phys. 136, 329 (2004).
• J. K. Viljas, Multiple Andreev Reflections in Weak Links of Superfluid ³He-B, Phys. Rev. B 71, 064509 (2005), cond-mat/0408430.
• E. V. Thuneberg, Theory of Josephson Phenomena in Superfluid ³He, AIP Conference Proceedings 850, 103 (2006), cond-mat/0509504.

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