Theoretical evidence for a reentrant phase diagram in {\em ortho-para} mixtures of solid H${}_2$

Abstract

We develop a multi order parameter mean-field formalism for systems of coupled quantum rotors. The scheme is developed to account for systems where {\it ortho-para} distinction is valid. We apply our formalism to solid H${}_2$ and D${}_2$. We find an anomalous {\it reentrant} orientational phase transition for both systems at thermal equilibrium. The correlation functions of the order parameter indicate short-range order at low temperatures. As temperature is increased the correlation increases along the phase boundary. We also find that even extremely small {\it odd-J} concentrations (1%) can trigger short-range orientational ordering.

4 pages, 5 figures, to appear in Physical Review Letters

References in corpus (2)

• Quantum and Classical Orientational Ordering in Solid Hydrogen
• Quantum Fluctuations Driven Orientational Disordering: A Finite-Size Scaling Study

Cited by in corpus (2)

• Mean-field theory of orientational ordering in rigid rotor models with identical atoms: spin conversion and thermal equilibration
• 2D and 3D quantum rotors in a crystal field: critical points, metastability, and reentrance