Journal of Low Temperature Physics

, Volume 187, Issue 5–6, pp 340–353 | Cite as

Electron Bubbles in Superfluid \(^3\)He-A: Exploring the Quasiparticle–Ion Interaction

  • Oleksii Shevtsov
  • J. A. SaulsEmail author


When an electron is forced into liquid \(^3\)He, it forms an “electron bubble”, a heavy ion with radius, \(R\simeq 1.5\) nm, and mass, \(M\simeq 100\,m_3\), where \(m_3\) is the mass of a \(^3\)He atom. These negative ions have proven to be powerful local probes of the physical properties of the host quantum fluid, especially the excitation spectra of the superfluid phases. We recently developed a theory for Bogoliubov quasiparticles scattering off electron bubbles embedded in a chiral superfluid that provides a detailed understanding of the spectrum of Weyl Fermions bound to the negative ion, as well as a theory for the forces on moving electron bubbles in superfluid \(^3\)He-A (Shevtsov and Sauls in Phys Rev B 94:064511, 2016). This theory is shown to provide quantitative agreement with measurements reported by the RIKEN group (Ikegami et al. in Science 341(6141):59, 2013) for the drag force and anomalous Hall effect of moving electron bubbles in superfluid \(^3\)He-A. In this report, we discuss the sensitivity of the forces on the moving ion to the effective interaction between normal-state quasiparticles and the ion. We consider models for the quasiparticle–ion (QP–ion) interaction, including the hard-sphere potential, constrained random-phase-shifts, and interactions with short-range repulsion and intermediate-range attraction. Our results show that the transverse force responsible for the anomalous Hall effect is particularly sensitive to the structure of the QP–ion potential and that strong short-range repulsion, captured by the hard-sphere potential, provides an accurate model for computing the forces acting on the moving electron bubble in superfluid \(^{3}\)He-A.


Superfluid \(^3\)He Electron bubbles Scattering theory t Matrix Weyl Fermions Broken parity and time-reversal Chirality 



The research of OS and JAS was supported by the National Science Foundation (Grant DMR-1508730). We thank Hiroki Ikegami, Kimitoshi Kono and Yasumasa Tsutsumi for discussions on their mobility experiments and interpretations.


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Copyright information

© Springer Science+Business Media New York 2016

Authors and Affiliations

  1. 1.Department of Physics and AstronomyNorthwestern UniversityEvanstonUSA

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