The internal energies of Heisenberg magnetic systems

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

卷:354

Article

Wang, Huai-Yu¹  Zhai, Liang-Jun¹  Qian, Meichun² 

[1] Tsinghua Univ, Dept Phys, Beijing 100084, Peoples R China

[2] Virginia Commonwealth Univ, Dept Phys, Richmond, VA 23284 USA

关键词: Internal energy;    Transverse correlation energy;    Longitudinal correlation energy;    Quantum fluctuation;    Green's function method;   

DOI  :  10.1016/j.jmmm.2013.11.024

来源: Elsevier

【 摘 要 】

The internal energies, including transverse and longitudinal parts, of quantum Heisenberg systems for arbitrary spin S are investigated by the double time Green's function method. The expressions for ferromagnetic (FM) and antiferromagnetic (AM) systems are derived when one component of magnetization is considered with the higher order longitudinal correlation functions being carefully treated. An unexpected result is that around the order-disorder transition points the neighboring spins in a FM (AFM) system are more likely longitudinally antiparallel (parallel) than parallel (antiparallel) to each other for S <= 3/2 in spite of the FM (AFM) exchange between the spins. This is attributed to the strong quantum fluctuation of the systems with small S values. We also present the expressions of the internal energies of FM systems when the three-component of magnetizations are considered. (C) 2013 Elsevier B.V. All rights reserved

【 授权许可】

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