Unconventional quantum ordered and disordered states in the highly frustrated spin-1/2 Ising-Heisenberg model on triangles-in-triangles lattices

Abstract

Ground state and thermodynamics of geometrically frustrated spin-1/2 Ising-Heisenberg model on two different but topologically related triangles-in-triangles lattices is investigated in particular. A rigorous mapping based on generalized star-triangle transformations enables one to derive exact analytical results for the free and internal energy, spontaneous magnetization, entropy and specific heat from the known exact results for the corresponding spin-1/2 Ising model on a triangular lattice. It is demonstrated that several unconventional quantum ordered and disordered phases may become the ground state in addition to the classical ferromagnetic phase with a perfect alignment of all constituent spins. A mutual competition between the ferromagnetic Ising and XXZ Heisenberg interactions may lead to an appearance of a peculiar quantum ferromagnetic phase, in which the magnetic moment of the Heisenberg spins undergoes a quantum reduction to one third of the saturation value in contrast with the fully saturated magnetic moment of the classical Ising spins. In the highly frustrated regime, we have found either the disordered quantum paramagnetic phase with the substantial residual entropy or a similar but strikingly spontaneously long-range ordered phase, in which a quantum reduction of the magnetic moment of the Heisenberg spins causes a small quantum reduction of the magnetic moment of otherwise purely classical Ising spins. It is evidenced that the specific heat exhibits diverse thermal dependences with or without a logarithmic divergence superimposed either on one or two round Schottky-type maxima.

16 pages, 13 figures

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• Generalized Transformation for Decorated Spin Models
• Generalized algebraic transformations and exactly solvable classical-quantum models
• High field properties of geometrically frustrated magnets
• Exact solution of the geometrically frustrated spin-1/2 Ising-Heisenberg model on the triangulated Kagome (triangles-in-triangles) lattice
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Cited by in corpus (10)

• Vigorous thermal excitations in a double-tetrahedral chain of localized Ising spins and mobile electrons mimic a temperature-driven first-order phase transition
• Correlation functions in one-dimensional spin lattices with Ising and Heisenberg bonds
• Is order-by-disorder present or absent in a highly frustrated region of the spin-1/2 Ising-Heisenberg model on triangulated Husimi lattices?
• Intermediate magnetization plateaus in the spin-1/2 Ising-Heisenberg and Heisenberg models on two-dimensional triangulated lattices
• Thermodynamic description of the Ising antiferromagnet on triangular lattice with selective dilution by modified Pair Approximation method
• Frustration phenomenon in the spin-1/2 Ising-Heisenberg planar model of inter-connected trigonal bipyramid structures
• Phase diagram and exotic spin-spin correlations of anisotropic Ising model on the Sierpiński gasket
• Geometrically frustrated Ising-Heisenberg spin model on expanded Kagomé lattice
• Chaotic spin-spin entanglement on a recursive lattice
• Emergence of quantum spin frustration in spin-1/2 Ising-Heisenberg model on a decorated honeycomb lattice