Experiemental studies of 1D quantum magnets with competing interactions

具有竞争相互作用的一维量子反铁磁体有望具有新颖的磁性。本研究对钻石链、三链和锯齿链模型化合物进行了研究。金刚石链模型化合物Cu3(A)2(OH)2(H2O)4的磁化曲线出现与1/3磁性平台有关的反常现象。我们研究了闪锌矿和闪锌矿，实际化合物的三链模型。闪锌矿的磁相图非常复杂，而闪锌矿则没有长程磁序。虽然这两种化合物的晶体结构相似，但它们的磁性却截然不同。结果表明，随着磁相互作用比例的变化，三链模型的基态可以发生量子相变。研究发现，锯齿状链状氧化物NaCr2O4具有巨大的磁阻效应。从自旋受挫效应的角度讨论了CMR效应的机理。

One dimensional quantum antiferromagets with competing interactions are expected to have novel magnetic properties. In this study, the diamond chain, triple-chain and zigzag chain model compounds were investigated. The magnetization curve of Cu3(A)2(OH)2(H2O)4, a diamond chain model compound, showed an anomaly related to the 1/3 magnetic plateau. We studied antlerite and szenicsite, actual compound for the triple-chain model. The magnetic phase diagram of antlerite is very complicated, while szenicsite has no long range magnetic order . Although crystal structures of both compounds are similar, their magnetic properties are quite different each other. It is suggested that a quantum phase transition could occur in the ground state of the triple-chain model as varying ratios among magnetic interactions. NaCr2O4, a zigzag chain oxide, was found to have the colossal magnetic resistance (CMR) effect. The mechanism of the CMR effect was discussed in terms of the spin frustration effect.