Dimensional Crossover in Quantum Antiferromagnets.

摘要: The dimensional crossover in a spin-S nearest-neighbor Heisenberg antiferromagnet is discussed as it tuned from two-dimensional square lattice, of lattice spacing a, towards spin chain by varying the width ${L}_{y}$ semi-infinite strip ${L}_{x}\ifmmode\times\else\texttimes\fi{}{L}_{y}$. For integer spins and arbitrary ${L}_{y}$, for half with ${L}_{y}/a$ an even integer, explicit analytical expressions zero temperature correlation length gap are given. odd argued that $c\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1$ behavior SU(2${)}_{1}$ Wess-Zumino-Witten fixed point squeezed out ${L}_{y}\ensuremath{\rightarrow}\ensuremath{\infty}$; here c conformal charge. results specialized to $S\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\frac{1}{2}$ applied spin-ladder systems.