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首页> 外文期刊>Physica Scripta: An International Journal for Experimental and Theoretical Physics >Local spin disorder in the magnetic kondo compounds CeNl(1-x)Cu(x)
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Local spin disorder in the magnetic kondo compounds CeNl(1-x)Cu(x)

机译：磁性近藤化合物CeNl（1-x）Cu（x）中的局部自旋

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摘要

Five members (x = 0.9. 0.6. 0.5. 0.4 and 0.2) of the strongly correlated electron compounds CeNi1-xCux have been studied using muSR spectroscopy. For 0.8 greater than or equal to x greater than or equal to 0.4 bulk magnetic data had indicated the existence of a spin-glasslike intermediate state between the long-range magnetic ordered (LRO) state at low temperatures and paramagnetism at higher temperatures. The measurements reported in this paper show that this intermediate magnetic state is unusual. its exact nature not being fully resolved. The muSR spectra for T less than or equal to 0.4 K are in all five compounds compatible with LRO. but show large transverse relaxation rates. In antiferromagnetic CeNi0.1Cu0.9 (T-N = 2.1 K mu(ord) = 1.45muB) this can be explained as originating from a complex spin structure. A second phase transition at 1.3 K was found. probably involving a spin reorientation. For x = 0.6 neutron diffraction data suggest collinear ferromagnetism while the large transverse relaxation indicates an additional substantial local spin disorder. Strong non-monotonic variations of the local field with x suggest different ordered spin structures at different compositions. In CeNi0.6Cu0.4 the muSR spectra indicate a spin arrangement containing a modulated spin component. The ordered Ce moment for CeNi0.8Cu0.2 is estimated to be approximate to0.1mu(B). confirming the reduction of moment with increasing Ni content due to the enhancement of the Kondo interaction. In all compounds except the v = 0.5 alloy an intermediate state. which is characterized in its pSR response by a high sensitivity to zero field cooling (ZFC) vs. field cooling (FC) history. was found. The dominant effect of FC is a slowing down of spin fluctuations. The muSR Spectra further revealed that the intermediate magnetic regime is neither a spin frozen state. nor a unique dynamically short-range correlated random spin state. but is characterized by a magnetic inhomogeneity with coexistence of an ordered and a non-ordered fraction. The latter increases strongly with temperature. The observation of a field history dependence is unusual in muSR studies of magnetically disordered materials and appears to be related to magnetic inhomogeneities. The magnetically diluted sample La0.25Ce0.75Ni0.8Cu0.2 was also studied. For this alloy, freezing into a randomly oriented spin state below 0.7 K was detected but no subsequent transition to LRO. Also for this alloy large field history effects were found. The local magnetic properties of CeNi1-xCux are discussed in terms of a cluster-type model. [References: 36]
机译：使用muSR光谱学研究了五种强相关电子化合物CeNi1-xCux（x = 0.9。0.6。0.5。0.4和0.2）。对于0.8大于或等于x大于或等于0.4，体磁数据表明在低温下的长程磁性有序（LRO）状态与高温下的顺磁性之间存在自旋玻璃状的中间状态。本文报道的测量结果表明，这种中间磁态是不寻常的。其确切性质尚未得到充分解决。在所有五种与LRO兼容的化合物中，T的muSR光谱小于或等于0.4K。但显示出较大的横向松弛率。在反铁磁CeNi0.1Cu0.9（T-N = 2.1 K mu（ord）= 1.45muB）中，这可以解释为源自复杂的自旋结构。发现在1.3 K的第二相变。可能涉及旋转重新定向。对于x = 0.6的中子衍射数据表明共线铁磁性，而较大的横向弛豫表明存在额外的实质性局部自旋失调。 x局部场的强非单调变化表明在不同的成分下具有不同的有序自旋结构。在CeNi0.6Cu0.4中，muSR光谱表明自旋排列包含调制的自旋成分。 CeNi0.8Cu0.2的有序Ce矩估计约为0.1mu（B）。证实了由于近藤相互作用的增强，镍含量增加而降低的力矩。在所有化合物中，除了v = 0.5合金以外，均为中间态。其pSR响应的特点是对零场冷却（ZFC）与场冷却（FC）历史的高度敏感性。被找到。 FC的主要作用是减慢自旋波动。 muSR谱进一步揭示了中间磁态既不是自旋冻结态。也不是唯一的动态短程相关随机自旋状态。但其特征是磁性不均匀，有序和无序部分共存。后者随温度强烈增加。磁场史相关性的观察在磁异常材料的muSR研究中是不寻常的，并且似乎与磁不均匀性有关。还研究了磁性稀释样品La0.25Ce0.75Ni0.8Cu0.2。对于这种合金，检测到冻结到低于0.7 K的随机取向的自旋态，但没有随后转变为LRO。同样对于这种合金，发现了大的场历史效应。 CeNi1-xCux的局部磁性能是根据簇模型进行讨论的。 [参考：36]

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