稀土锰氧化物Ln0 .7Ba0.3MnO3（Ln = Nd或Gd）铁磁态和非磁绝缘态的玻璃化行为
Glassy behavior in the ferromagnetic and the non-magnetic insulating states of the rare earth manganates, Ln0.7Ba0.3MnO3 (Ln = Nd or Gd)
摘要：
而La0.7Ba0.3MnO3是一种铁磁金属（TC = 340 K）与长程有序，Nd0.7Ba0.3MnO3显示出一个转变约150 K的磁化强度略有增加，但在所有温度下仍然是一个绝缘体。Gd0.7Ba0.3MnO3在所有温度下都是非磁性和绝缘的。低场直流磁化强度和交流磁化率测量揭示了在Nd0.7Ba0.3MnO3中在150 K左右存在一个转变，并且在62，46和36 K的情况下，Gd0.7Ba0.3MnO3具有不同的有序/冻结转变的复杂行为，最后一个更突出。的磁化强度的场依赖性的性质，结合缓慢的磁弛豫，老化和记忆效应，表明Nd0.7Ba0.3MnO3是低于150 K，一个类似的情况下发现的La_{1-x} SrxCoO 3的簇玻璃。而Gd_（0.7）Ba_（0.3）MnO_3在36 K以下表现出自旋玻璃的非平衡动力学特征。Gd0.7Ba0.3MnO3和Nd0.7Ba0.3MnO3之间的玻璃化行为的性质的差异可能是由于前者中A位阳离子的尺寸之间的失配引起的较大的无序。我们的研究结果表明，Nd 0.7Ba 0.3MnO 3和Gd 0.7Ba 0.3MnO 3的磁绝缘状态经常报告的稀土锰氧化物类型的Ln 1-xAxMnO 3（Ln =稀土，A =碱土金属）可能与玻璃态磁行为。
英文摘要：
While La0.7Ba0.3MnO3 is a ferromagnetic metal (TC = 340 K) with longrange ordering, Nd0.7Ba0.3MnO3 shows a transition around 150 K with a small increase in magnetization, but remains an insulator at all temperatures. Gd0.7Ba0.3MnO3 is non-magnetic and insulating at all temperatures. Low field dc magnetization and ac susceptibility measurements reveal the presence of a transition at around 150 K in Nd0.7Ba0.3MnO3, and a complex behavior with different ordering/freezing transitions at 62, 46 and 36 K in the case of Gd0.7Ba0.3MnO3, the last one being more prominent. The nature of the field dependence of the magnetization, combined with the slow magnetic relaxation, ageing and memory effects, suggests that Nd0.7Ba0.3MnO3 is a cluster glass below 150 K, a situation similar to that found for La_{1-x}SrxCoO3. Gd0.7Ba0.3MnO3, however, shows non-equilibrium dynamics characteristic of spin glasses, below 36 K. The difference in nature of the glassy behavior between Gd0.7Ba0.3MnO3 and Nd0.7Ba0.3MnO3 probably arises because of the larger disorder arising from the mismatch between the sizes of the A-site cations in the former. Our results on Nd0.7Ba0.3MnO3 and Gd0.7Ba0.3MnO3 suggest that the magnetic insulating states often reported for rare earth manganates of the type Ln1-xAxMnO3 (Ln = rare earth, A = alkaline earth) are likely to be associated with glassy magnetic behavior.
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