By high temperature series expansion and exact complete diagonalization the magnetic susceptibility chi(T) and the specific heat C(T) of a two-leg S=1/2 ladder with cyclic (4-spin) exchange are computed. Both methods yield convincing results for not too small temperatures. We find that a small amount of cyclic exchange influences the thermodynamical properties significantly. Our results can serve as reliable basis for an efficient analysis of experimental data
@article{arxiv.cond-mat/0210669,
title = {Thermodynamic Properties of Spin Ladders with Cyclic Exchange},
author = {Alexander Buehler and Ute Loew and Kai P. Schmidt and Goetz S. Uhrig},
journal= {arXiv preprint arXiv:cond-mat/0210669},
year = {2009}
}