Electron Mobility at Low Temperatures in Liquid 3He

International Workshop on Electrons and Ions in Quantum Fluids and Solids

Authors: James A. Sauls
Department of Physics & Astronomy, Northwestern University, Evanston, IL 60208
March 11-14, 2018

Abstract: Just over sixty years ago parity violation by the weak force was demonstrated in experiments led by C. S. Wu on the asymmetry of electron currents emitted in the beta decay of polarized 60Co with respect to mirror reflection. That same year Bardeen, Cooper and Schrieffer published the celebrated BCS theory of superconductivity. As a tribute to these discoveries I present experimental and theoretical results on parity violation in a BCS superfluid. The light isotope, 3He, undergoes BCS condensation below 2×10−3 Kelvin. Under a wide range of conditions the vacuum state (3He-A) is a condensate of chiral p-wave molecular pairs of 3He atoms, which spontaneously breaks parity and time-reversal symmetry. An electron embedded in 3He-A polarizes the condensate and inherits signatures of the parity-violating vacuum. In particular, electrons embedded in liquid 3He-A form a self-trapped ion - an "electron bubble" - with a mass, M ≈ 100 m3, a radius R ≈ 2 nm and an angular momentum, J ≈ 100 ħ. Experimental signatures include the anomalous Hall effect for electron transport in superfluid 3He-A, providing a direct detection of parity violation and broken time-reversal symmetry by the chiral ground state of 3He.1 I present the theory of the anomalous Hall effect for electrons moving in the chiral phase of 3He, and explain the origin of the transverse force on an electron moving in a gas of chiral fermions at low but finite temperatues. % I also discuss the break-down failure of the scattering theory at ultra-low temperatures, present results for the mobility of liquid 3He at ultra-low temperatures.

1. H. Ikegami, Y. Tsutsumi, & K. Kono, Chiral Symmetry in Superfluid 3He-A, Science, 341,59-62, 2013.

2. O. Shevtsov & J. A. Sauls, Electrons & Weyl Fermions in Superfluid 3He-A, Phys. Rev. B, 94, 064511, 2016.

This research was supported by NSF Grant: DMR-1508730

Slides: [PDF]

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Last update: March 15, 2018