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Mirko Todorovski - One of the best experts on this subject based on the ideXlab platform.

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Yuriy Sizyuk - One of the best experts on this subject based on the ideXlab platform.

  • free energy of quantum spin systems functional integral representation
    Physical Review B, 2017
    Co-Authors: P Wolfle, Natalia B Perkins, Yuriy Sizyuk
    Abstract:

    In this work, we propose a method for calculating the free energy of anisotropic quantum spin systems. We use the Hubbard-Stratonovich transformation to express the partition function of a generic bilinear superexchange Hamiltonian in terms of a functional integral over classical time-dependent fields. In the general case the result is presented as a product of traces over single spins subject to a time-dependent field. The traces may be evaluated in closed form in the case of systems with large Ising anisotropy. In the general case we derive a Compact Expression for the contribution of Gaussian spin fluctuations to the free energy. We show how anisotropic spin interactions lead to anisotropies in the free energy, giving rise to pinning of the spontaneous magnetization along preferred directions

Amarpreet Rattan - One of the best experts on this subject based on the ideXlab platform.

Darius Germanas - One of the best experts on this subject based on the ideXlab platform.