Generalized antiferromagnetic Heisenberg spin ladders

宏光 堀, Shoji Yamamoto

Jialiang Li, Jialin Zhong, Xuefan Jiang

Toshihiko Suzuki, Yuichi Watabe, Hitoshi Takeuchi +5 more

Mohamed Moussadek Azzouz, K. A. Asante

The antiferromagnetic Heisenberg model on the three-leg ladder is studied using the generalized Jordan-Wigner transformation in dimensions higher than 1, and the bond-mean-field theory. The magnetic susceptibility and other thermodynamic quantities are analyzed as a function of the rung-to-leg coupling ratio $\ensuremath{\alpha}$ and temperature $T$. We fit the experimental susceptibility data of the three-leg material ${\mathrm{Sr}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{5}$ of Azuma and co-workers with good agreement. One of the main findings of this work is the proposal that close to two-thirds of the spin degrees of freedom on each of the rungs of the ladder lock at low $T$ for small $\ensuremath{\alpha}$, then collectively almost $2∕3$ of the spin degrees of freedom on all the rungs freeze completely at low $T$ for $\ensuremath{\alpha}$ greater than a threshold value. The approach developed here can be used to study the three-leg ladder for all values of $\ensuremath{\alpha}$, and is thus suitable for the description of the crossover regime between the weak- and strong-coupling regimes.

Alexei M. Tsvelik

J. Piekarewicz, James R. Shepard