Intermediate spin and quantum critical points, etc
Abstract
Unlike that of SO(3) or SU(2), the Lie algebra for SO(2), which defines intermediate spin, comprises only $S_{z}$ and implies $S^{\pm}$ commute. In general, $S_{z}$ has a continuous spectrum. This intermediate spin scheme can realized for the low energy excitations of a wide class of large spin magnets. A magnetic field provides the necessary time reversal symmetry breaking and controls the effective value of the spin $\tilde S$. Physical quantities are periodic in the equilibrium magnetization component induced by this field. In particular for one dimensional antiferromagnets there are periodic regions on the field axis for which the model is quantum critical while in two or three dimensions criticality is reduced to points.
 Publication:

arXiv eprints
 Pub Date:
 January 1999
 arXiv:
 arXiv:condmat/9901219
 Bibcode:
 1999cond.mat..1219B
 Keywords:

 Statistical Mechanics;
 Mesoscopic Systems and Quantum Hall Effect
 EPrint:
 17 pages, including one figure