Detta är en digital seminarieserie i kondenserade materiens fysik och atomfysik, med syfte att koppla samman forskare från olika nordiska universitet. Samtalen är informella och ska inspirera till diskussioner och interaktioner.
Abstract
The normal liquid 3He conforms to Landau’s Fermi liquid picture, but only at very low temperature (<20 mK). We have recently shown that its thermal conductivity [1] can be accounted for in the whole temperature range (0.01 K-3 K), by assuming that it is the sum of two contributions: one by quasi-particles (varying as the inverse of temperature) and another by a hydrodynamic sound mode (following the square root of temperature) [2]. The first component has been known for decades. The second is a collective [sound] mode [3] with a ~2kF wave-vector in the hydrodynamic limit. Our expression for it, derived from Landauer’s formula, is a quantum version of the Bridgman equation for thermal conductivity of classical liquids. The quadratic electrical resistivity of Fermi liquids offers its own puzzles [4]. The deviation from this behavior in strongly correlated Fermi liquids well below the Fermi temperature may be accounted for by the presence of such a collective mode.
[1] D. S. Greywall, Phys. Rev. B 29, 4933 (1984).
[2] K. Behnia & K. Trachenko, Nature Commun. 15, 1771 (2024).
[3] F. Albergamo et al., Phys. Rev. Lett. 99, 205301 (2007).
[4] X. Lin, B. Fauqué & K . Behnia, Science 349, 6251 (2015).
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