Experimental data for the uniform susceptibility, magnetization and specific heat for the material Cu2(C5H12N2)2Cl4 (abbreviated CuHpCl) as a function of temperature and external field are compared with those of three different dimerized spin models: alternating spin-chains, spin-ladders and the bilayer Heisenberg model. It is shown that because this material consists of weakly coupled spin-dimers, much of the data is insensitive to how the dimers are coupled together and what the effective dimensionality of the system is. When such a system is tuned to the quantum critical point by application of a field, the dimensionality shows up in the power-law dependences of thermodynamic quantities on temperature. We discuss the temperature window for such a quantum critical behavior in CuHpCl.
@article{arxiv.cond-mat/9803085,
title = {Field dependent thermodynamics and Quantum Critical Phenomena in the dimerized spin system Cu2(C5H12N2)2Cl4},
author = {Norbert Elstner and Rajiv R. P. Singh},
journal= {arXiv preprint arXiv:cond-mat/9803085},
year = {2009}
}