Quadrupolar glass freezing in solid hydrogen: Distribution functions for the orientational axial and eccentric order parameters

Journal Article · Wed Dec 01 00:00:00 EST 1993 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.48.15658· OSTI ID:5630024

Kopec, T K ^[1]

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1. Theoretische Tieftemperaturphysik, University of Duisburg, Lotharstrasse 1, 47048 Duisburg 1 (Germany)

The microscopic model for two-dimensional distribution function [ital P]([sigma],[eta]) for quadrupolar glass freezing of axial ([sigma]) and eccentric ([eta]) order parameters in solid hydrogen is considered within the Sherrington-Kirkpatrick mean-field approach. Assuming the exchange interactions between axial and eccentric quadrupoles to be independent Gaussian random variables with variance [ital J][sup 2]/[ital N] and [ital K][sup 2]/[ital N], respectively (with [ital N] being the number of lattice sites), we derived a set of self-consistent equations for quadrupolar order parameters and the corresponding local susceptibilities. While for [ital J][ne][ital K] the axial quadrupolar order parameter is nonvanishing in the high-temperature phase due to broken local symmetry and the corresponding quadrupolar susceptibility exhibits smeared-out behavior, the eccentric order parameter becomes zero at well-defined critical temperature depending on the ratio [ital K]/[ital J]. Furthermore, the properties of the [ital P]([sigma],[eta]) distribution function are investigated by introducing a single effective order parameter [sigma][sub [ital e][ital f][ital f]] (1[lt][sigma][sub [ital e][ital f][ital f]][lt]0) directly related to the second frequency moment of the nuclear magnetic resonance line shapes. Comparison of the present microscopic theory with earlier phenomenological approaches to the problem is also made.

• OSTI ID: 5630024
• Journal Information: Physical Review, B: Condensed Matter; (United States), Vol. 48:21; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
HYDROGEN
ORDER-DISORDER TRANSFORMATIONS
DISTRIBUTION FUNCTIONS
FREEZING
GLASS
MEAN-FIELD THEORY
ORDER PARAMETERS
ORIENTATION
QUADRUPOLES
SOLIDS
ELEMENTS
FUNCTIONS
MULTIPOLES
NONMETALS
PHASE TRANSFORMATIONS
665430* - Other Topics in Quantum Fluids & Solids- (1992-)