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arXiv · 1305.6039

PbCu3TeO7: An S=1/2 staircase Kagome lattice with significant intra- and inter-plane couplings

B. Koteswararao·R. Kumar·Jayita Chakraborty·Byung-Gu Jeon·A. V. Mahajan·I. Dasgupta·Kee Hoon Kim·F. C. Chou
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Abstract

We have synthesized polycrystalline and single crystal samples of PbCu3TeO7 and studied its properties via magnetic susceptibility chi(T) and heat-capacity Cp(T) measurements and also electronic structure calculations. Whereas the crystal structure is suggestive of the presence of a quasi-2D network of Cu2+ (S = 1/2) buckled staircase Kagome layers, the chi(T) data show magnetic anisotropy and three magnetic anomalies at temperatures, TN1 ~ 36 K, TN2 ~ 25 K, TN3 ~ 17 K, respectively. The chi(T) data follow the Curie-Weiss law above 200 K and a Curie-Weiss temperature Theta_CW ~ -150 K is obtained. The data deviate from the simple Curie-Weiss law below 200 K, which is well above TN1, suggesting the presence of competing magnetic interactions. The magnetic anomaly at TN3 appears to be of first-order from magnetization measurements, although our heat-capacity Cp(T) results do not display any anomaly at TN3. The hopping integrals obtained from our electronic structure calculations suggest the presence of significant intra-Kagome (next-nearest neighbor and diagonal) and inter-Kagome couplings. These couplings take the PbCu3TeO7 system away from a disordered ground state and lead to long-range order, in contrast to what might be expected for an ideal (isotropic) 2D Kagome system.

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B. Koteswararao, R. Kumar, Jayita Chakraborty, Byung-Gu Jeon, A. V. Mahajan, I. Dasgupta, Kee Hoon Kim, F. C. Chou. 2013-05-26. PbCu3TeO7: An S=1/2 staircase Kagome lattice with significant intra- and inter-plane couplings. https://doi.org/10.1088/0953-8984%2F25%2F33%2F336003

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