Experimental Observation of the Increase of the Two-Dimensional Critical Temperature in Multilayer Adsorption

Abstract

Measurements of multilayer adsorption of solid 4 He on graphite have been made for 0.965 K^ T^ 1.24 K at intervals of ~ 15 mK using fourth sound in He II as a probe. The first observation of the increase of the two-dimensional critical temperature T cj with increasing layer number j is reported. We extrapolate our values of T cj for j -• oo and obtain the bulkroughening transition temperature, confirming a prediction of current theories. The modeling of the acoustics including effects of the solid-liquid interface is also presented.

Observation of two-stage layering transitions for solidHe4on graphite

“…In addition, one can precisely control the density of steps and kinks as a function of pressure and temperature. Previous measurements [11,12] are in excellent agreement with the variational theory of Weeks [13] for multilayer solid absorption and the predicted [14] increase of the two-dimensional critical temperature with increasing layer numbers. In this paper we report a clear observation of a two-stage layering transition which appears at temperatures below 0.95 K and in layers at least as high as the eighth (the highest transition observable in our experiment).…”

Layering Transitions of the Spin-1/2 Ising Model in a Transverse Magnetic Field

“…One type of transitions is the layering transitions, in which the thickness of a typically solid film increases discontinuously by one layer as the pressure is increased. Such transitions have been observed in a variety of systems including for example 4 He [5] and ethylene adsorbed on graphite [6]. The n-th layering transition from a n À 1 layer film to an n layer film, typically is only present at low temperatures and may terminate as the temperature increases in a layering critical point T cY n aJ which belongs to the universality class of the twodimensional Ising model.…”

Layering Transition in Superfluid Helium Adsorbed on a Carbon Nanotube Mechanical Resonator

“…The layering transitions are rounded, probably because the layering transitions have a critical point of order 1 K (see Ref. [27]). By varying the gate voltage, consequently the spring constant, we have confirmed that the variation of the resonance frequency f 0 in Fig.…”