Absence of Substrate Nucleation for bcc SolidHe3on Grafoil

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

“…Thus, it seems to be clear that, even under an external pressure from the liquid phase of 3He, there is no continuous formation of solid layers of 3He on Grafoil. These results contradict the conclusions of Landau and Eckstein [4,8] that continuous nucleation takes place when the symmetry of the monolayer matches the symmetry of the adjacent bulk solid lattice. Following this argument, the missing symmetry between the triangular monolayer [13,14] and the bcc 3He solid can prevent nucleation as observed in our experiment.…”

“…One of the isopycnals in the bcc region (II) is shown with a more extended scale in figure 2. In agreement with the results of Landau and Eckstein [8] in another temperature range (30 mK T 320 mK), no rounding of the isopycnal in the vicinity of the melting curve, which , L' 'J Fig. 1.…”

“…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).…”