Self-consistent model of a solid for the description of lattice and magnetic properties

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

卷:426

Article

Balcerzak, T.¹  Szalowski, K.¹  Jascur, M.² 

[1] Univ Lodz, Fac Phys & Appl Informat, Dept Solid State Phys, Ulica Pomorska 149-153, PL-90236 Lodz, Poland

[2] Safarik Univ, Fac Sci, Dept Theoret Phys & Astrophys, Pk Angelinum 9, Kosice 04154, Slovakia

关键词: Magnetoelastic coupling;    Ferromagnetism;    Thermodynamics of magnets;    Curie temperature;    Magnetization;    Thermal expansion;    Isothermal compressibility;   

DOI  :  10.1016/j.jmmm.2016.11.107

来源: Elsevier

【 摘 要 】

In the paper a self-consistent theoretical description of the lattice and magnetic properties of a model system with magnetoelastic interaction is presented. The dependence of magnetic exchange integrals on the distance between interacting spins is assumed, which couples the magnetic and the lattice subsystem. The framework is based on summation of the Gibbs free energies for the lattice subsystem and magnetic subsystem. On the basis of minimization principle for the Gibbs energy, a set of equations of state for the system is derived. These equations of state combine the parameters describing the elastic properties (relative volume deformation) and the magnetic properties (magnetization changes). The formalism is extensively illustrated with the numerical calculations performed for a system of ferromagnetically coupled spins S= 1/2 localized at the sites of simple cubic lattice. In particular, the significant influence of the magnetic subsystem on the elastic properties is demonstrated. It manifests itself in significant modification of such quantities as the relative volume deformation, thermal expansion coefficient or isothermal compressibility, in particular, in the vicinity of the magnetic phase transition. On the other hand, the influence of lattice subsystem on the magnetic one is also evident. It takes, for example, the form of dependence of the critical (Curie) temperature and magnetization itself on the external pressure, which is thoroughly investigated.

【 授权许可】

Free