Eur. Phys. J. B (2012) 85: 54
https://doi.org/10.1140/epjb/e2011-20733-5

Regular Article

Spontaneous distortion in the spin-1/2 Ising-Heisenberg model on decorated planar lattices with a magnetoelastic coupling

¹ Department of Theoretical Physics and Astrophysics, Faculty of Science, P. J. Šafárik University, Park Angelinum 9, 04001 Košice, Slovak Republic
² Departamento de Ciencias Exatas, Universidade Federal de Lavras, CP 3037, 37200000, MG, Brazil

^a e-mail: jozef.strecka@upjs.sk

Received: 4 September 2011
Received in final form: 15 November 2011
Published online: 8 February 2012

Abstract

Magnetoelastic properties of the spin-1/2 Ising-Heisenberg model on doubly decorated planar lattices partially amenable to lattice vibrations are examined within the framework of the harmonic approximation and decoration-iteration transformation. It is shown that the magnetoelastic coupling may lead to a spontaneous distortion of the vibrating decorating atoms and the mutual interplay between quantum spin fluctuations and local lattice deformations enhances typical quantum features like the quantum reduction of the magnetization in the ground state of the quantum antiferromagnetic phase, while it does not affect the ground-state behaviour of the classical ferromagnetic phase. It also turns out that the spontaneous distortion is responsible for a much more pronounced reduction of the critical temperature in the quantum antiferromagnetic phase than in the classical ferromagnetic phase.