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arXiv 1507.01740cond-mat.str-el
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三角形反铁磁体La2Ca2MnO7中的磁序、自旋波和涨落

Magnetic order, spin waves and fluctuations in the triangular antiferromagnet La2Ca2MnO7

P. Dalmas de Réotier, C. Marin, A. Yaouanc, T. Douce, A. Sikora, A. Amato, C. Baines

摘要:

本文报道了在T_N = 2.8 K以下的三角形反铁磁体La_2Ca_2MnO_7的磁化率、比热和μ子自旋弛豫(muSR)实验结果。La_2Ca_2MnO_7在T_N = 2.8 K以下形成了真正的二维、三子晶格\sqrt{3} \times \sqrt{3}。从磁化率和比热数据的交换相互作用的估计。从后者的数据中获得的自旋波间隙的值。先前报道的非弹性中子散射研究的分析产生的交换和自旋波间隙的值与从宏观测量获得的结果兼容。一个明显的熵仍然失踪在10 K,可能是由于强烈的短程相关。临界顺磁涨落的范围远大于T_N,并且可以部分地用二维自旋波激发来理解。在T_N以下没有观察到自发的μ SR场,但发现了持续的自旋动力学,在此温度范围内检测到了短程关联。它们之间的关系,一个可能的分子自旋子结构和所观察到的奇异自旋波动进行了讨论。

英文摘要:

We report magnetic susceptibility, specific heat and muon spin relaxation (muSR) experiments on the triangular antiferromagnet La2Ca2MnO7 which develops a genuine two-dimensional, three-sublattice \sqrt{3} \times \sqrt{3} magnetic order below T_N = 2.8 K. From the susceptibility and specific heat data an estimate of the exchange interaction is derived. A value for the spin-wave gap is obtained from the latter data. The analysis of a previously reported inelastic neutron scattering study yields values for the exchange and spin-wave gap compatible with the results obtained from macroscopic measurements. An appreciable entropy is still missing at 10 K that may be ascribed to intense short-range correlations. The critical paramagnetic fluctuations extend far above T_N, and can be partly understood in terms of two-dimensional spin-wave excitations. While no spontaneous muSR field is observed below T_N, persistent spin dynamics is found. Short-range correlations are detected in this temperature range. Their relation to a possible molecular spin substructure and the observed exotic spin fluctuations is discussed.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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