Effect of the boundary condition on the Kapitza resistance between superfluid 3He-B and sintered metal

Autti, Samuli and Guénault, Tony and Jennings, Ash and Haley, Richard and Pickett, George and Schanen, Roch and Tsepelin, Viktor and Vonka, Jakub and Zmeev, Dmitry and Soldatov, Arkady (2020) Effect of the boundary condition on the Kapitza resistance between superfluid 3He-B and sintered metal. Physical Review B: Condensed Matter and Materials Physics, 102: 064508. ISSN 2469-9950

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Abstract

Understanding the temperature dependence of thermal boundary resistance, or Kapitza resistance, between liquid helium and sintered metal has posed a problem in low temperature physics for decades. In the ballistic regime of superfluid 3He-B, we find the Kapitza resistance can be described via scattering of thermal excitations (quasiparticles) with a macroscopic geometric area, rather than the sintered metal's microscopic area. We estimate that a quasiparticle needs on the order of 1000 collisions to successfully thermalize with the sinter. Finally, we find that the Kapitza resistance is approximately doubled with the addition of two mono-layers of solid 4He on the sinter surface, which we attribute to an extra magnetic channel of heat transfer being closed as the non-magnetic solid 4He replaces the magnetic solid 3He.