Abstract. Ground-state and finite-temperature properties of the mixed spin-1 2 and spin-S Ising-Heisenberg diamond chains are examined within an exact analytical approach based on the generalized decoration-iteration map. A particular emphasis is laid on the investigation of the effect of geometric frustration, which is generated by the competition between Heisenberg-and Ising-type exchange interactions. It is found that an interplay between the geometric frustration and quantum effects gives rise to several quantum ground states with entangled spin states in addition to some semiclassically ordered ones. Among the most interesting results to emerge from our study one could mention a rigorous evidence for quantized plateux in magnetization curves, an appearance of the round minimum in the thermal dependence of susceptibility times temperature data, double-peak zero-field specific heat curves, or an enhanced magnetocaloric effect when the frustration comes into play. The triple-peak specific heat curve is also detected when applying small external field to the system driven by the frustration into the disordered state.PACS numbers: 05.50.+q, 75.10.Hk, 75.10.Jm, 75.10.Pq, 75.40.Cx Submitted to: J. Phys.: Condens. Matter
IntroductionOver the last three decades, the low-dimensional quantum spin models with competing (frustrated) interactions have attracted considerable research interest especially due to their extraordinary diverse ground-state behaviour. Geometrically frustrated spin systems constitute a special sub-class of the frustrated models that can be distinguished by incapability of spins, inherent in their lattice positions, to simultaneously minimize the ground-state energy of each individual spin-spin interaction [1]. As a rule, the quantum spin systems affected by a rather strong geometric frustration often exhibit an exotic non-magnetic ground state (which does not have its classical analogue) in addition to a rich variety of the semi-classically ordered ones [2]. It is worthy to notice, moreover, ‡ Corresponding author: jozkos@pobox.sk [25], for which precise analytic solution is available leastwise for the ground state. Nevertheless, it should be pointed out that frustrated quantum systems are in general rather difficult to deal with, since extensive numerical methods must be used in order to obtain a reliable estimate of their magnetic properties. From this point of view, the one-dimensional (1D) frustrated spin systems are the simplest systems with respect to accurate treatment. Of these systems, the spin- [33]. Another remarkable finding relates to the observation of an inversion phenomenon, which can be induced in the frustrated diamond chain through the exchange anisotropy [34,35]. Note that the ground state and thermodynamics of the mixed-spin diamond chains containing also higher-spin sites have already been particularly examined as well [36]-[40].It is worthwhile to remark that 1D frustrated spin systems have initially been introduced purely as toy models suitable for investigating the ...
Thermodynamic properties of a tetramer ferro-ferro-antiferro-antiferromagnetic Ising-Heisenberg bond alternating chain are investigated by the use of an exact mapping transformation technique. Exact results for the magnetization, susceptibility and specific heat in the zero as well as nonzero magnetic field are presented and discussed in detail. The results obtained from the mapping are compared with the relevant experimental data of Cu(3-Clpy)2(N3)2 (3-Clpy=3-Chloropyridine).
Applying the decoration-iteration procedure, we introduce a class of exactly solvable doubly decorated planar models consisting both of the Ising-and Heisenberg-type atoms. Exact solutions for the ground state, phase diagrams and basic physical quantities are derived and discussed. The detailed analysis of the relevant quantities suggests the existence of an interesting quantum antiferromagnetic phase in the system.
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