Title: Exact solution of the mixed spin-1/2 and spin-S Ising-Heisenberg diamond chain
Author(s):

	L. Čanová (Department of Applied Mathematics, Faculty of Mechanical Engineering, Technical University, Letná 9, 042 00 Košice, Slovak Republic) ,
	J. Strečka (Department of Theoretical Physics and Astrophysics, Faculty of Science, P. J. Šafárik University, Park Angelinum 9, 040 01 Košice, Slovak Republic) ,
	T. Lučivjanský (Department of Theoretical Physics and Astrophysics, Faculty of Science, P. J. Šafárik University, Park Angelinum 9, 040 01 Košice, Slovak Republic)

The geometric frustration in a class of the mixed spin-1/2 and spin-S Ising-Heisenberg diamond chains is investigated by combining three exact analytical techniques: Kambe projection method, decoration-iteration transformation and transfer-matrix method. The ground state, the magnetization process and the specific heat as a function of the external magnetic field are particularly examined for different strengths of the geometric frustration. It is shown that the increase of the Heisenberg spin value S raises the number of intermediate magnetization plateaux, which emerge in magnetization curves provided that the ground state is highly degenerate on behalf of a sufficiently strong geometric frustration. On the other hand, all intermediate magnetization plateaux merge into a linear magnetization versus magnetic field dependence in the limit of classical Heisenberg spin S → ∞. The enhanced magnetocaloric effect with cooling rate exceeding the one of paramagnetic salts is also detected when the disordered frustrated phase constitutes the ground state and the external magnetic field is small enough.

Key words: Ising-Heisenberg model, diamond chain, geometric frustration, exact results
PACS: 05.30.-d, 05.50.+q, 75.10.Hk, 75.10.Jm, 75.10.Pq, 75.40.Cx
Comments: Figs. 7, Refs. 56, Tabs. 0

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