Tetrahedral Quantum Magnets in One and Two Dimensions

Adam Iaizzi

Wolfram Brenig, K. W. Becker

We discuss the magnetic properties of a dimerized and completely frustrated tetrahedral spin-1/2 chain. Using a combination of exact diagonalization and bond-operator theory the quantum phase diagram is shown to incorporate a singlet product, a dimer, and a Haldane phase. In addition we consider one- and two-triplet excitations in the dimer phase and evaluate the magnetic Raman cross section which is found to be strongly renormalized by the presence of a two-triplet bound state. The link to a novel tellurate materials is clarified.

Kiyohito Totsuka, H.-J. Mikeska

We investigate low-lying singlet and triplet excitations and the magnetization process of quasi-one-dimensional spin systems composed of tetrahedral spin clusters. For a class of such models, we found various exact low-lying excitations; some of them are responsible for the first-order transition between two different ground states formed by local singlets. Moreover, we find that there are two different kinds of magnetization plateaus which are separated by a first-order transition.

Yu. B. Kudasov, R. V. Kozabaranov

Olesia Krupnitska

We consider the spin-1/2 antiferromagnetic Heisenberg model on two one-dimensional frustrated lattices, a double-tetrahedral chain and an octahedral chain, with almost dispersionless (flat) lowest magnon band in a strong magnetic field. Using the localized-magnon picture, we construct an effective description of the one-dimensional chains with triangle and square traps within the strong-coupling approximation. We perform extensive exact diagonalization and density matrix renormalization group calculations to check the validity of the obtained effective Hamiltonians by comparison with the initial models with special focus on the magnetization and specific heat at high magnetic fields.

Eric Seewald, Lalit Yadav, Sachith Dissanayake +2 more