Title: Magnetoelastic properties of a spin-1/2 Ising-Heisenberg diamond chain in vicinity of a triple coexistence point
Author(s):

	N. Ferreira (Departamento de Física, Universidade Federal de Lavras CP 3037, 37200-900, Lavras - MG, Brazil),
	J. Torrico (Departamento de Física, Universidade Federal de Minas Gerais, C. P. 702, 30123-970, Belo Horizonte, Mg, Brazil),
	S.M. de Souza (Departamento de Física, Universidade Federal de Lavras CP 3037, 37200-900, Lavras - MG, Brazil),
	O. Rojas (Departamento de Física, Universidade Federal de Lavras CP 3037, 37200-900, Lavras - MG, Brazil),
	J. Streška (Department of Theoretical Physics and Astrophysics, Faculty of Science, P.J. Šafárik University, Park Angelinum 9, 040 01 Košice, Slovakia)

We study magnetoelastic properties of a spin-1/2 Ising-Heisenberg diamond chain, whose elementary unit cell consists of two decorating Heisenberg spins and one nodal Ising spin. It is assumed that each couple of the decorating atoms including the Heisenberg spins harmonically vibrates perpendicularly to the chain axis, while the nodal atoms involving the Ising spins are placed at rigid positions when ignoring their lattice vibrations. An effect of the magnetoelastic coupling on a ground state and finite-temperature properties is particularly investigated close to a triple coexistence point depending on a spring-stiffness constant ascribed to the Heisenberg interaction. The magnetoelastic nature of the Heisenberg dimers is reflected through a non-null plateau of the entropy emergent in a low-temperature region, whereas the specific heat displays an anomalous peak slightly below the temperature region corresponding to the entropy plateau. The magnetization also exhibits a plateau in the same temperature region at almost saturated value before it gradually tends to zero upon increasing of temperature. The magnetic susceptibility displays within the plateau region an inverse temperature dependence, which slightly drops above this plateau, whereas an inverse temperature dependence is repeatedly recovered at high enough temperatures.

Key words: magnetoelastic chain, spin magnetization, thermodynamics

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