Coexistence of vortex arrays and surface capillary waves in spinning prolate superfluid He-4 nanodroplets

Abstract

Within Density Functional Theory, we have studied the interplay between vortex arrays and capillary waves in spinning prolate He-4 droplets made of several thousands of helium atoms. Surface capillary waves are ubiquitous in prolate superfluid He-4 droplets and, depending on the size and angular momentum of the droplet, they may coexist with vortex arrays. We have found that the equilibrium configuration of small prolate droplets is vortex-free, evolving towards vortex-hosting as the droplet size increases. This result is in agreement with a recent experiment [S.M. O'Connell et al., Phys. Rev. Lett. 124, 215301 (2020)], where it has been disclosed that vortex arrays and capillary waves coexist in the equilibrium configuration of very large drops. Contrarily to viscous droplets executing rigid body rotation, the stability phase diagram of spinning He-4 droplets cannot be universally described in terms of dimensionless angular momentum and angular velocity variables: instead, the rotational properties of superfluid helium droplets display a clear dependence on the droplet size and the number of vortices they host.

11 pages, 6 figures

References in corpus (7)

• Density Functional Theory of doped superfluid liquid helium and nanodroplets
• Vortex arrays in nanoscopic superfluid helium droplets
• Vorticity and quantum turbulence in the merging of superfluid Helium nanodroplets
• Shapes of rotating normal fluid 3He versus superfluid 4He droplets in molecular beams
• Vortex arrays in a rotating superfluid He-4 nanocylinder
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Cited by in corpus (3)

• Vortices in quantum droplets of heteronuclear Bose mixtures
• Nanoscopic jets and filaments of superfluid He-4 at zero temperature: a DFT study
• Merging of superfluid Helium nanodroplets with vortices