Isotope-Induced Quantum-Phase Transitions in the Liquid State

Abstract

Isotopic binary liquid mixtures are universally characterized by an upper critical solution temperature as a consequence of zero-point motion in conjunction with the anharmonicity of the interatomic potential. This quantum effect is predicted, and demonstrated by small-angle neutron-scattering measurements, to be manifest at ambient temperatures for mixtures of deuterated and protonated polymers. Prior evidence of such phase behavior has been restricted to liquid mixtures of $^{3}\mathrm{He}$ and $^{4}\mathrm{He}$.