Phase transition temperatures of 405-725 K in superfluid ultra-dense hydrogen clusters on metal surfaces (original) (raw)

Superfluidity and Quantum Melting of para-Hydrogen clusters

Phys Rev Lett, 2006

Structural and superfluid properties of para-Hydrogen clusters of size up to N=40 molecules, are studied at low temperature (0.5 K < T < 4 K) by Path Integral Monte Carlo simulations. The superfluid fraction displays an interesting, non-monotonic behavior for 22 < N < 30. We interpret this dependence in terms of variations with N of the cluster structure. Superfluidity is observed at low T in clusters of as many as 27 molecules; in the temperature range considered here, quantum melting is observed in some clusters, which freeze at high temperature.

Superfluid Hydrogen in Nanoscale Confinement

2014

Confinement is known to suppress order in condensed matter. This is well exemplified in phase transitions such as freezing, as well as the superfluid transition in liquid helium, which occur at lower temperatures in confinement than in the bulk. We provide in this thesis a demonstration of a physical setting in which the reverse takes place. Particularly, the enhancement of the superfluid response of parahydrogen confined to nanoscale size cavities is illustrated by means of first principle computer simulations. Prospects to stabilize and observe the long investigated but yet elusory bulk superfluid phase of parahydrogen in objectively designed porous media are discussed.