Orateur
Description
When the electron mean-free-path exceeds the sample thickness in a metal, Sondheimer oscillations of electric conductivity, which are periodic in magnetic field, can emerge. Our study of longitudinal and transverse conductivity in cadmium single crystals with thicknesses ranging from 12.6 to 475 μm demonstrate that the amplitude of the first ten oscillations is determined by the quantum of conductance and a length scale that depends on the sample thickness, the magnetic length and the Fermi surface geometry [1]. In the same crystals, one observes a low temperature size-dependent resistivity upturn in a finite window sandwiched between ballistic and diffusive regimes [2]. Within this window, the electrical conductivity displays a simultaneous quadratic dependence on both sample size and temperature, which is a fingerprint of hydrodynamic flow. This leads us to quantify the amplitude and the temperature dependence of kinematic and dynamic viscosity of the electron fluid. The rate of momentum-conserving e-e collisions is not set by the main Fermi energy, but by Lilliputian energy scales and inter-valley bottlenecks.
1. Xiaodong Guo, Xiaokang Li, Lingxiao Zhao, Zengwei Zhu & Kamran Behnia, Communications Materials 7, 76 (2026).
2. Xiaodong Guo, Xiaokang Li, Benoît Fauqué, Alaska Subedi, Lingxiao Zhao, Zengwei Zhu, Kamran Behnia, arXiv:2604.19416 (2026).
