Supersolid {sup 4}He likely has nearly isotropic superflow
- Department of Physics, Texas A and M University, College Station, Texas 77843 (United States)
We extend previous calculations of the zero temperature upper bound for the superfluid fraction f{sub s} vs localization, from the fcc lattice to the experimentally realized (for solid {sup 4}He) hcp and bcc lattices. The superfluid velocity is assumed to be a one-body function, and dependent only on the local density, taken to be a sum over sites of Gaussians of width {sigma}. Localization is defined as {sigma}/d, with d the nearest-neighbor distance. As expected, for fcc and bcc lattices the superfluid density tensor is proportional to the unit tensor. To numerical accuracy of three places (but no more), the hcp superfluid density tensor is proportional to the unit tensor. This implies that a larger spread in data on f{sub s}, if measured on pure crystals, is unlikely to be due to crystal orientation. In addition, to three decimal places (but no more) the curves of f{sub s} vs {sigma}/d are the same for both the hcp and fcc cases. An expected value for the localization gives an f{sub s} in reasonable agreement with experiment. The bcc lattice has a similar curve of f{sub s} vs {sigma}/d, but is generally smaller because the lattice is more dilute.
- OSTI ID:
- 20787947
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 73, Issue 9; Other Information: DOI: 10.1103/PhysRevB.73.092505; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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