Absence of continuous nucleation for solid⁴He on MgO

Absence of continuous growth for bcc and hcp solid 3He on Grafoil

“…Thus, following the classification of adsorption of Dash [5] and Peierls [6], these two systems have been found to be of Class I (uniform deposits at all thicknesses). On the other hand, thermodynamic [4,7] and neutron scattering investigations [7] of 4He on the cubic structure MgO and thermodynamic measurements of 3 He on Grafoil [8] in the temperature range from 30 mK to 320 mK show no evidence for continuous nucleation of a surface solid, classifying these systems as Class II (bulk nucleation after a thin uniform deposit).…”