Geometric frustration in the class of exactly solvable Ising–Heisenberg diamondchains

Abstract

Ground-state and finite-temperature properties of the mixed spin- and spin-S Ising–Heisenberg diamond chains are examined within an exact analytical approachbased on the generalized decoration–iteration map. A particular emphasis is laidon the investigation of the effect of geometric frustration, which is generatedby the competition between Heisenberg- and Ising-type exchange interactions.It is found that an interplay between the geometric frustration and quantumeffects gives rise to several quantum ground states with entangled spin states inaddition to some semi-classically ordered ones. Among the most interesting results toemerge from our study one could mention rigorous evidence for quantized plateauxin magnetization curves, an appearance of the round minimum in the thermaldependence of susceptibility times temperature data, double-peak zero-field specific heatcurves, or an enhanced magnetocaloric effect when the frustration comes intoplay. The triple-peak specific heat curve is also detected when applying smallexternal field to the system driven by the frustration into the disordered state.