Quantum criticalities in a two-leg antiferromagnetic S=12 ladder induced by a staggered magnetic field
Y. J. Wang, Fabian H. L. Eßler, Michele Fabrizio +1 more
We study a two-leg antiferromagnetic spin-1/2 ladder in the presence of a staggered magnetic field. We consider two parameter regimes: strong (weak) coupling along the legs and weak (strong) coupling along the rungs. In both cases, the staggered field drives the Haldane spin-liquid phase of the ladder towards a Gaussian quantum criticality. In a generalized spin ladder with a non-Haldane, spontaneously dimerized phase, the staggered magnetic field induces an Ising quantum critical regime. In the vicinity of the critical lines, we derive low-energy effective field theories and use these descriptions to determine the dynamical response functions, the staggered spin susceptibility, and the string order parameter.
arXiv:cond-mat/0112249•Physical review. B, Condensed matter•Jul 2, 2002•41 citations