We have performed a quantum Monte Carlo study of a two-dimensional bulk sample of interacting 1/2-spin structureless fermions, a model of He-3 adsorbed on a variety of preplated graphite substrates. We have computed the equation of state and the polarization energy using both the standard fixed-node approximate technique with a simple backflow trial function and a formally exact methodology, relying on bosonic imaginary-time correlation functions of operators suitably chosen in order to extract fermionic energies. As the density increases, the fixed-node approximation predicts a transition to an itinerant ferromagnetic fluid, whereas the unbiased methodology indicates that the paramagnetic fluid is the stable phase until crystallization takes place. We find that two-dimensional He-3 at zero temperature crystallizes from the paramagnetic fluid at a density of 0.061 angstrom(-2) with a narrow coexistence region of 0.002 angstrom(-2). Remarkably, the spin susceptibility turns out in very good agreement with experiments.

Equation of state of two-dimensional He-3 at zero temperature / M. Nava, A. Motta, D. E. Galli, E. Vitali, S. Moroni. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - 85:18(2012), pp. 184401.184401.1-184401.184401.7. [10.1103/PhysRevB.85.184401]

Equation of state of two-dimensional He-3 at zero temperature

D.E. Galli;E. Vitali
Penultimo
;
2012

Abstract

We have performed a quantum Monte Carlo study of a two-dimensional bulk sample of interacting 1/2-spin structureless fermions, a model of He-3 adsorbed on a variety of preplated graphite substrates. We have computed the equation of state and the polarization energy using both the standard fixed-node approximate technique with a simple backflow trial function and a formally exact methodology, relying on bosonic imaginary-time correlation functions of operators suitably chosen in order to extract fermionic energies. As the density increases, the fixed-node approximation predicts a transition to an itinerant ferromagnetic fluid, whereas the unbiased methodology indicates that the paramagnetic fluid is the stable phase until crystallization takes place. We find that two-dimensional He-3 at zero temperature crystallizes from the paramagnetic fluid at a density of 0.061 angstrom(-2) with a narrow coexistence region of 0.002 angstrom(-2). Remarkably, the spin susceptibility turns out in very good agreement with experiments.
Settore FIS/03 - Fisica della Materia
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/180230
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