Possible observation of surface and special transitions in mixtures

Abstract

We point out a possible mechanism for physically realizing surface and special (or surface-bulk) transitions in binary mixtures. Impurities which affect the critical temperature may interact with the wall and thus enhance the effective interaction of the components in its vicinity. The same mechanism applies to the already observed superfluid film formation near a wall in ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ mixtures, in the proximity of the $\lambda$ line.