Quantum fluctuations in anisotropic triangular lattices with ferro- and antiferromagnetic exchange

Abstract

The Heisenberg model on a triangular lattice is a prime example for a geometrically frustrated spin system. However most experimentally accessible compounds have spatially anisotropic exchange interactions. As a function of this anisotropy, ground states with different magnetic properties can be realized. Motivated by recent experimental findings on Cs${}_2$CuCl${}_{4-x}$Br${}_x$, we discuss the full phase diagram of the anisotropic model with two exchange constants $J_1$ and $J_2$, including possible ferromagnetic exchange. Furthermore a comparison with the related square lattice model is carried out. We discuss the zero-temperature phase diagram, ordering vector, ground-state energy, and ordered moment on a classical level and investigate the effect of quantum fluctuations within the framework of spin-wave theory. The field dependence of the ordered moment is shown to be nonmonotonic with field and control parameter.

13 pages, 14 figures

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Cited by in corpus (4)

• Frustrated two dimensional quantum magnets
• Signatures of indirect K-edge resonant inelastic x-ray scattering on magnetic excitations in triangular lattice antiferromagnet
• Néel temperature and reentrant H-T phase diagram of quasi-2D frustrated magnets
• Spin Excitation Spectra of Spin-Orbit Coupled Bosons in Optical Lattice