Low Temperature Physics: 33, 920 (2007); https://doi.org/10.1063/1.2747066 (7 pages)
Физика Низких Температур: Том 33, Выпуск 11 (Ноябрь 2007), c. 1213-1221    ( к оглавлению , назад )

Quantum phase transitions and thermodynamics of quantum antiferromagnets with competing interactions

Christian Trippe and Andreas Klümper

Fachbereich C – Physik, Bergische Universität Wuppertal, 42097 Wuppertal, Germany
E-mail: trippe@physik.uni-wuppertal.de

Received March 26, 2007


We study the isotropic Heisenberg chain with nearest and next-nearest neighbor interactions. The ground state phase diagram is constructed in dependence on the additional interactions and an external magnetic field. The thermodynamics is studied by use of finite sets of nonlinear integral equations resulting from integrability. The equations are solved numerically and analytically in suitable limiting cases. We find second and first order transition lines. The exponents of the low-temperature asymptotics at the phase transitions are determined.

PACS: 75.10.Jm Quantized spin models;
PACS: 75.10.Pq Spin chain models;
PACS: 75.40.–s Critical-point effects, specific heats, short-range order.

Ключевые слова: integrable systems, thermodynamics, critical behavior, Bethe-ansatz.