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Model formalism of paramagnetic solid helium-3

Model formalism of paramagnetic solid helium-3 The statistical-thermodynamic formalism of a collection of localized spin-1/2 atoms whose spin Hamiltonian refers to the isotropic antiferromagnetic Heisenberg exchange-interaction scheme is applied here to account for a set of important equilibrium-thermodynamic measurements on paramagnetic solid3He performed some time ago by University of Florida investigators. The measured properties were the temperature-dependent modulations of the pressure, which were proved earlier to arise overwhelmingly from the nuclear spin system. The present formalism of the pressure modulations or of the spin pressures, along specified isochores of the solid, includes the density- or molar-volume-dependent microscopic exchange energy parameter and its derivative. In this paper we have derived directly hitherto unavailable exact values of these parameters from spin pressure data on magnetized solid3He, as well as indirectly through the intermediary of spin pressures in the absence of a magnetic field. The directly derived exact parameters result from a single characteristic equilibrium-thermodynamic state of the solid in the presence of a constant and uniform magnetic field of adequate strength. The indirectly derived but exact parameters, of possibly somewhat lower accuracy, require the knowledge of a single directly derived exchange-energy parameter together with a set of spin pressures of asymptotic high-temperature equilibrium states in the absence of a magnetic field. The indirectly derived microscopic parameters along two of the three experimentally explored magnetized solid isochores yielded calculated spin pressures in fair and acceptable agreement, respectively, with their measured values. The directly derived exact parameters used in calculating the spin pressures along the third experimentally investigated isochore, in the absence of a magnetic field and at three different field strengths, led to complete agreement with the data. These results lend support to the tentative proposition advanced in early work that over a range of temperatures and molar volumes of paramagnetic solid3He, the statistical-thermodynamic formalism based on the antiferromagnetic exchange-interaction scheme may give an acceptable account of the spin pressures as well as of other thermal properties of this quantum solid. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Low Temperature Physics Springer Journals

Model formalism of paramagnetic solid helium-3

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References (8)

Publisher
Springer Journals
Copyright
Copyright
Subject
Physics; Condensed Matter Physics; Characterization and Evaluation of Materials; Magnetism, Magnetic Materials
ISSN
0022-2291
eISSN
1573-7357
DOI
10.1007/BF00661146
Publisher site
See Article on Publisher Site

Abstract

The statistical-thermodynamic formalism of a collection of localized spin-1/2 atoms whose spin Hamiltonian refers to the isotropic antiferromagnetic Heisenberg exchange-interaction scheme is applied here to account for a set of important equilibrium-thermodynamic measurements on paramagnetic solid3He performed some time ago by University of Florida investigators. The measured properties were the temperature-dependent modulations of the pressure, which were proved earlier to arise overwhelmingly from the nuclear spin system. The present formalism of the pressure modulations or of the spin pressures, along specified isochores of the solid, includes the density- or molar-volume-dependent microscopic exchange energy parameter and its derivative. In this paper we have derived directly hitherto unavailable exact values of these parameters from spin pressure data on magnetized solid3He, as well as indirectly through the intermediary of spin pressures in the absence of a magnetic field. The directly derived exact parameters result from a single characteristic equilibrium-thermodynamic state of the solid in the presence of a constant and uniform magnetic field of adequate strength. The indirectly derived but exact parameters, of possibly somewhat lower accuracy, require the knowledge of a single directly derived exchange-energy parameter together with a set of spin pressures of asymptotic high-temperature equilibrium states in the absence of a magnetic field. The indirectly derived microscopic parameters along two of the three experimentally explored magnetized solid isochores yielded calculated spin pressures in fair and acceptable agreement, respectively, with their measured values. The directly derived exact parameters used in calculating the spin pressures along the third experimentally investigated isochore, in the absence of a magnetic field and at three different field strengths, led to complete agreement with the data. These results lend support to the tentative proposition advanced in early work that over a range of temperatures and molar volumes of paramagnetic solid3He, the statistical-thermodynamic formalism based on the antiferromagnetic exchange-interaction scheme may give an acceptable account of the spin pressures as well as of other thermal properties of this quantum solid.

Journal

Journal of Low Temperature Physics – Springer Journals

Published: Nov 3, 2004

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