Pair approximation method for spin-1 Heisenberg system

Mert M., Kilic A., MERT G.

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, vol.402, pp.101-104, 2016 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 402
  • Publication Date: 2016
  • Doi Number: 10.1016/j.jmmm.2015.11.050
  • Journal Name: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.101-104
  • Keywords: Heisenberg ferromagnet, Pair approximation method, Phase transition, BIQUADRATIC EXCHANGE, ISING FERROMAGNET, THERMODYNAMIC PROPERTIES, PHASE-TRANSITIONS, OGUCHI METHOD, IRON-GARNET, MAGNETIZATION, FIELD
  • Ankara University Affiliated: Yes

Abstract

Spin-1 Heisenberg system on simple cubic lattice is considered in the pair approximation method assuming that the second-nearest-neighbor exchange interaction parameter has a negative value. The system is described in presence of an external magnetic field. The effects of the negative single-ion anisotropy and the negative second-nearest-neighbor exchange interaction on magnetization, internal energy, heat capacity, entropy and free energy are investigated. There are diverse anomalies at low temperature. In the magnetization and other thermodynamic quantities, the first-order phase transitions from ferromagnetic state to antiferromagnetic state and from ferromagnetic state to paramagnetic state have been observed. (C) 2015 Elsevier B.V. All rights reserved.