Magnetic order in the S=1/2 two-dimensional molecular antiferromagnet copper pyrazine perchlorate Cu(Pz)2(ClO4)2
Magnetic order in the S=1/2 two-dimensional molecular antiferromagnet copper pyrazine perchlorate Cu(Pz)2(ClO4)2
Lancaster, T.; Blundell, S. J.; Brooks, M. L.; Baker, P. J.; Pratt, F. L.; Manson, J. L.; Conner, M. M.; Xiao, F.; Landee, C. P.; Chaves, F. A.; Soriano, S.; Novak, M. A.; Papageorgiou, T. P.; Bianchi, A. D.; Herrmannsdörfer, T.; Wosnitza, J.; Schlueter, J. A.
We present an investigation of magnetic ordering in the two-dimensional S=1/2 quantum magnet Cu(Pz)2(ClO)4)2 using specific heat and zero-field muon-spin relaxation (µ+SR). The magnetic contribution to the specific heat is consistent with an exchange strength of 17.7(3) K. We find unambiguous evidence for a transition to a state of three-dimensional long-range order below a critical temperature TN=4.21(1) K using µ+SR even though there is no feature in the specific heat at that temperature. The absence of a specific heat anomaly at TN is consistent with recent theoretical predictions. The ratio of TN/J=0.24 corresponds to a ratio of intralayer to interlayer exchange constants of |J´ /J| =6.8x10−4, indicative of excellent two-dimensional isolation. The scaled magnetic specific heat of [Cu(Pz)2(HF2)]BF4, a compound with an analogous structure, is very similar to that of Cu(Pz)2(ClO)4)2 although both differ slightly from the predicted value for an ideal 2D S=1/2 Heisenberg antiferromagnet.
- Physical Review B 75(2007), 094421
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