Chatterji T, Demmel F, Jalarvo N, Podlesnyak A, Kumar C M N, Xiao Y, Brückel T
Institut Laue-Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France.
J Phys Condens Matter. 2017 Nov 29;29(47):475802. doi: 10.1088/1361-648X/aa9245. Epub 2017 Nov 2.
In order to understand the origin of the huge quasielastic magnetic scattering observed previously with a back-scattering neutron spectrometer, we have re-investigated the low energy excitations in HoCrO by inelastic neutron scattering in a much wider energy range with time-of-flight neutron spectrometers. The inelastic signals are due to the excitations between the ground state doublet of the Ho ion. The quasielastic signal is due to the fluctuation of the disordered Ho moments. At low temperature the intensity of quasielastic scattering is small. It starts increasing as the temperature increases above 30 K. At the same temperature, the elastic intensity due to Ho moment ordering decreases in a similar way. This observation strengthens the hypothesis that the quasielastic scattering is due the fluctuations of the disordered Ho moments. The time scale of fluctuations has been determine from the quasielastic scattering and was found to vary from about 22 ps at [Formula: see text] K to about 2.5 ps at [Formula: see text] K. The stretched exponential line shape indicates a distribution of decay rates at low temperatures.
为了理解先前使用背散射中子谱仪观测到的巨大准弹性磁散射的起源，我们利用飞行时间中子谱仪在更宽的能量范围内通过非弹性中子散射重新研究了HoCrO中的低能激发。非弹性信号源于Ho离子基态双重态之间的激发。准弹性信号源于无序Ho磁矩的涨落。在低温下，准弹性散射强度较小。当温度升至30 K以上时，它开始增加。在相同温度下，由于Ho磁矩有序化产生的弹性强度以类似方式降低。这一观测结果强化了准弹性散射源于无序Ho磁矩涨落的假设。涨落的时间尺度已根据准弹性散射确定，发现其在[公式：见原文]K时约为22 ps，在[公式：见原文]K时约为2.5 ps。拉伸指数线形表明在低温下存在衰减率分布。
