School of Physics, University of Melbourne, Parkville, Victoria 3010, Australia.
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Phys Rev Lett. 2015 Mar 13;114(10):106101. doi: 10.1103/PhysRevLett.114.106101. Epub 2015 Mar 11.
MnFePSi compounds are promising materials for magnetic refrigeration as they exhibit a giant magnetocaloric effect. From first principles calculations and experiments on bulk materials, it has been proposed that this is due to the Mn and Fe atoms preferentially occupying two different sites within the atomic lattice. A recently developed technique was used to deconvolve the obscuring effects of both multiple elastic scattering and thermal diffuse scattering of the probe in an atomic resolution electron energy-loss spectroscopy investigation of a MnFePSi compound. This reveals, unambiguously, that the Mn atoms preferentially occupy the 3g site in a hexagonal crystal structure, confirming the theoretical predictions. After deconvolution, the data exhibit a difference in the Fe L_{2,3} ratio between the 3f and 3g sites consistent with differences in magnetic moments calculated from first principles, which are also not observed in the raw data.
MnFePSi 化合物是用于磁制冷的有前途的材料，因为它们表现出巨大的磁热效应。通过对块状材料的第一性原理计算和实验，人们提出这是由于 Mn 和 Fe 原子优先占据原子晶格内的两个不同位置。最近开发的一种技术用于分解在 MnFePSi 化合物的原子分辨率电子能量损失光谱研究中探针的多重弹性散射和热漫散射的模糊影响。这毫不含糊地表明，Mn 原子优先占据六方晶体结构中的 3g 位，证实了理论预测。去卷积后，数据在 3f 和 3g 位之间表现出 Fe L_{2,3} 比的差异，与第一性原理计算的磁矩差异一致，而在原始数据中未观察到这种差异。
