Probing the A- B Phase Interface in Superfluid 3He by Andreev Reflection of a Quasiparticle Beam

D. J. Cousins; M. P. Enrico; S. N. Fisher; S. L. Phillipson; G. R. Pickett; N. S. Shaw; P. J. Y. Thibault

doi:10.1103/PhysRevLett.77.5245

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Probing the A- B Phase Interface in Superfluid 3He by Andreev Reflection of a Quasiparticle Beam

D. J. Cousins, M. P. Enrico, S. N. Fisher, S. L. Phillipson, G. R. Pickett, N. S. Shaw, P. J. Y. Thibault

DOI 10.1103/PhysRevLett.77.5245 · Physical Review Letters

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Abstract

Using a ballistic excitation beam generated by a quasiparticle blackbody radiator, we have probed the gap structure of a B−A interface in superfluid 3He, stabilized magnetically. We see Andreev reflection both from the interface and from the field-distorted B-phase gap. As Andreev processes return excitations to the radiator enclosure, the fraction reflected governs the radiator temperature, from which we infer the maximum spin-dependent quasiparticle gap as a function of magnetic field. These measurements are the first to probe the superfluid 3He phase interface with quasiparticles.