Doležal Petr, Cejpek Petr, Tsutsui Satoshi, Kaneko Koji, Legut Dominik, Carva Karel, Javorský Pavel
Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Charles University, Ke Karlovu 5, 121 16, Prague 2, Czech Republic.
Japan Synchrotron Radiation Research Institute (JASRI), SPring-8, Sayo, Hyogo, 679-5198, Japan.
Sci Rep. 2021 Oct 22;11(1):20878. doi: 10.1038/s41598-021-99904-7.
The interaction between phonons and 4f electrons, which is forming a new quantum state (quasi-bound state) beyond Born-Oppenheimer approximation, is very prominent and lattice dynamics plays here a key role. There is only a small number of compounds in which the experimental observation suggest such a scenario. One of these compounds is CePdAl. Here the study of phonon dispersion curves of (Ce,La)PdAl at 1.5, 7.5, 80 and 300 K is presented. The inelastic X-ray scattering technique was used for mapping the phonon modes at X and Z points as well as in Λ and Δ directions, where the symmetry analysis of phonon modes was performed. The measured spectra are compared with the theoretical calculation, showing very good agreement. The measurements were performed in several Brillouin zones allowing the reconstruction of phonon dispersion curves. The results are discussed with respect to the magneto-elastic interaction and are compared with other cerium compounds. The phonon mode symmetry A was found to be unaffected by the interaction, which is in contrast to previous assumptions.
声子与4f电子之间的相互作用非常显著，这种相互作用形成了一种超越玻恩-奥本海默近似的新量子态（准束缚态），晶格动力学在此起着关键作用。仅有少数化合物的实验观测结果表明存在这种情况。其中一种化合物是CePdAl。本文展示了对(Ce,La)PdAl在1.5 K、7.5 K、80 K和300 K时声子色散曲线的研究。非弹性X射线散射技术用于绘制X和Z点以及Λ和Δ方向的声子模式，同时对声子模式进行了对称性分析。将测量光谱与理论计算进行比较，结果显示出非常好的一致性。测量在几个布里渊区进行，从而能够重建声子色散曲线。结合磁弹性相互作用对结果进行了讨论，并与其他铈化合物进行了比较。发现声子模式对称性A不受该相互作用的影响，这与之前的假设相反。
