POSSIBLE SUPERFLUID PHASE OF PARAHYDROGEN ON NANOPATTERNED SURFACES

• Author / Creator

  Idowu, Saheed A

• We study by computer simulations the low temperature properties of small parahydrogen clusters (free clusters) and the effect of confinement on the energetics
  and superfluid properties in two-dimensions (2D). Computed energetics
  for the free clusters are in quantitative agreement with that reported in the
  only previous study [M. C. Gordillo and D. M. Ceperley, Phys. Rev. B 65,
  174527 (2002)], but a generally strong superfluid response is obtained for clusters
  with more than ten molecules. All the free clusters, including the smallest
  one, feature a well-defined, clearly identifiable solidlike structure; with only
  one possible exception, those with fewer than N = 25 molecules are (almost)
  entirely superfluid at the lowest temperature considered (i.e., T = 0.25 K),
  and are thus referred to as nanoscale “supersolids”. The superfluid response
  in the low temperature limit of the confined clusters is found to remain commensurable
  in magnitude to that of the free clusters, for clusters fewer than twenty molecules, within a wide range of depth and size of the confining well.
  The flexibility of the superfluid response is traceable to the “supersolid” character
  of these clusters. We explore the possibility of establishing a bulk 2D
  superfluid “cluster crystal” phase of p-H2, in which a global superfluid response
  would arise from tunnelling of molecules across adjacent unit cells. Computed
  energetics suggests that for a cluster of about ten molecules, such a phase may
  be thermodynamically stable against the formation of the equilibrium insulating
  crystal, for values of cluster crystal lattice constant possibly allowing
  tunnelling across adjacent unit cells.

• Subjects / Keywords

  • Supersolid
  • Superfluidity
  • Bose Einstein condensation

• Graduation date

  Fall 2015

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3SQ8QR8P

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.