Faculté des sciences

Exotic phases in geometrically frustrated triangular Ising magnets

Jiang, Ying ; Emig, Thorsten

In: Journal of Physics: Condensed Matter, 2007, vol. 19, no. 14, p. 145234

We report a systematic study of both quantum and classical geometrically frustrated Ising models with competing ordering mechanism. The ordering comes in the classical case from a coupling of two-dimensional (2D) layers and in the quantum model from the quantum dynamics induced by a transverse field. We develop a microscopic derivation of the Landau–Ginzburg–Wilson (LGW) Hamiltonian for these... More

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    Summary
    We report a systematic study of both quantum and classical geometrically frustrated Ising models with competing ordering mechanism. The ordering comes in the classical case from a coupling of two-dimensional (2D) layers and in the quantum model from the quantum dynamics induced by a transverse field. We develop a microscopic derivation of the Landau–Ginzburg–Wilson (LGW) Hamiltonian for these models and show that it can be interpreted as the free energy of three-dimensional (3D) elastic non-crossing strings. By utilizing this effective Hamiltonian, the entire transverse field versus temperature phase diagram for the 2D quantum Ising model is obtained analytically, including the universality classes of both the quantum and the finite temperature transitions. The structures of the ordered phases in both 3D classical and 2D quantum Ising models are obtained from a detailed entropy argument. The results are in excellent agreement with recent numerical simulations.