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Title: Evidence for a Common Physical Origin of the Landau and BEC Theories of Superfluidity

There are two renowned theories of superfluidity in liquid 4He, quite different and each with specific domains of application. In the first, the Landau theory, superflow follows from the existence of a well-defined collective mode supported by dense liquid 4He, the phonon-roton mode. In the second, superflow is a manifestation of Bose-Einstein condensation (BEC) and phase coherence in the liquid. We present combined measurements of superfluidity, BEC and phonon-roton (P-R) modes in liquid 4He confined in the porous medium MCM-41. The results integrate the two theories by showing that well-defined P-R modes exist where there is BEC. The two are common properties of a Bose condensed liquid and either can be used as a basis of a theory of superfluidity. In addition, the confinement and disorder suppresses the critical temperature for superfluidity, Tc, below that for BEC creating a localized BEC phase consisting of islands of BEC and P-R modes. This phase is much like the pseudogap phase in the cuprate superconductors.
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [3] ;  [4] ;  [5] ;  [5]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Quantum Condensed Matter Division
  2. National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States). Center for Neutron Research; Univ. of Maryland, College Park, MD (United States). Dept. of Materials Science and Engineering
  3. Univ. of Electro-Communications, Chofu, Tokyo (Japan). Dept. of Engineering Science
  4. Centre National de la Recherche Scientifique (CNRS), Grenoble (France). Inst. Neel
  5. Univ. of Delaware, Newark, DE (United States). Dept. of Physics and Astronomy
Publication Date:
OSTI Identifier:
1286799
Grant/Contract Number:
AC05-00OR22725; FG02-03ER46038
Type:
Accepted Manuscript
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 113; Journal Issue: 21; Journal ID: ISSN 0031-9007
Publisher:
American Physical Society (APS)
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY Bose-Einstein Condensation; Superfluidity; Roton; MCM-41; Inelastic Neutron