用多区声子精化法确定SrFe2As2的声子谱
Phonon spectrum of SrFe2As2 determined using multizone phonon refinement
摘要：
铁磷族化合物超导体在晶格和磁自由度之间表现出敏感的相互作用，包括许多声子模式，这些声子模式比使用密度泛函理论（DFT）的DFT计算所预测的要软得多。然而，尚不清楚长程磁序对23 meV以上的声子频率有什么影响（如果有的话），其中几个声子分支在能量上非常接近，并且将它们彼此隔离是具有挑战性的。我们测量这些声子使用非弹性飞行时间中子散射在约40布里渊区，并开发了一种技术来确定它们的频率。我们发现这种方法能够确定声子能量~0.1毫电子伏的精度，并使用实验结构的DFT计算产生定性正确的能量和本征矢量。我们没有发现磁跃迁对这些声子的影响。
英文摘要：
The ferropnictide superconductors exhibit a sensitive interplay between the lattice and magnetic degrees of freedom, including a number of phonon modes that are much softer than predicted by nonmagnetic calculations using density functional theory (DFT). However, it is not known what effect, if any, the long-range magnetic order has on phonon frequencies above 23 meV, where several phonon branches are very closely spaced in energy and it is challenging to isolate them from each other. We measured these phonons using inelastic time-of-flight neutron scattering in ~40 Brillouin zones, and developed a technique to determine their frequencies. We find this method capable of determining phonon energies to ~0.1 meV accuracy, and that the DFT calculations using the experimental structure yield qualitatively correct energies and eigenvectors. We do not find any effect of the magnetic transition on these phonons.
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