Ground state and low-lying excitations in the Heisenberg XXZ chain of arbitrary spin S

Leon A. Takhtajan

A. Honecker, D. C. Cabra, Marcelo D. Grynberg +5 more

Tom Michoel, Bruno Nachtergaele

We present new results and give a concise review of recent previous results on the asymptotics for large spin of the low-lying spectrum of the ferromagnetic XXZ Heisenberg chain with kink boundary conditions. Our main interest is to gain detailed information on the interface ground states of this model and the low-lying excitations above them. The new and most detailed results are obtained using a rigorous version of bosonization, which can be interpreted as a quantum central limit theorem.

Shoji Yamamoto, Seiji Miyashita

Onofre Rojas, Francisco Castilho Alcaraz

The phase diagram of a coupled tetrahedral Heisenberg model is obtained. The quantum chain has a local gauge symmetry and its eigenspectrum is obtained by the composition of the eigenspectra of $\mathrm{s}\mathrm{p}\mathrm{i}\mathrm{n}\ensuremath{-}\frac{1}{2}$ XXZ chains with arbitrary distribution of $\mathrm{s}\mathrm{p}\mathrm{i}\mathrm{n}\ensuremath{-}\frac{3}{2}$ impurities. The phase diagram is quite rich with an infinite number of phases with ferromagnetic, antiferromagnetic, or ferrimagnetic order. In some cases the ground state and the low-lying eigenlevels of the model can be exactly calculated since they coincide with the eigenlevels of the exactly integrable XXZ chain. The thermodynamical properties of the model at low temperatures are also studied through finite-size analysis.

Vladyslav O. Cheranovskii