On the properties of vacancies in solid 4 He as studied by pressure measurements
P. Remeijer, S. C. Steel, R. Jochemsen, and G. Frossati
Kamerlingh Onnes Laboratorium, Leiden University P. O. Box 9506, 2300 RA Leiden, The Netherlands
J. M. Goodkind
Physics Department 0319, University of California at San Diego 9600 Gilman Drive,La Jolla, CA 92037, U.S.A.
( Submitted November 26, 1996 )
We have measured the temperature dependence of the pressure at constant volume in solid 4He in the low density hcp phase. The measurements are analysed in terms of a localized vacancy model and the free Bose gas model of vacancies in solid helium. The results agree better with the free Bose gas model. Within this model we have determined the effective mass of the vacancies to be 3-5 times the bare mass of a 4He atom, corresponding to a bandwidth of 1.3-2.1 K