Gomes M M, Vilarinho R, Zhao H, Íñiguez-González J, Mihalik M, Mihalik M, Maia A, Goian V, Nuzhnyy D, Kamba S, Moreira J Agostinho
IFIMUP, LaPMET, Departamento de Física e Astronomia da Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre S/N, 4169-007, Porto, Portugal.
Key Laboratory of Material Simulation Methods and Software of Ministry of Education, College of Physics, Jilin University, Changchun, 130012, China.
Sci Rep. 2024 Jul 4;14(1):15378. doi: 10.1038/s41598-024-66594-w.
The possibility of inducing new polar and/or magnetic transient states through the pumping of optical phonons towards the non-linear regime has renewed the scientific interest in orthoferrites. Nonetheless, to perform these studies it is fundamental to have a deep knowledge of the lattice excitations at equilibrium conditions. In this work, we present a complete characterization of the optically-active zone-center phonons in NdFeO single crystals at room temperature by means of polarized Raman and infrared spectroscopies. The study is complemented with polarized infrared spectroscopy at 4 K and unpolarized Raman scattering at 10 K. The predicted polar phonons were successfully observed together with some of the crystal-field excitations. First-principles simulations further allow the eigenmode and symmetry assignments of the optical phonons. The calculated atomic motions of each mode are of significant interest, as they are common for all orthoferrites and to most of the large family of orthorhombic Pbnm perovskites.
通过向非线性 regime 泵浦光学声子来诱导新的极性和/或磁性瞬态的可能性，重新激发了科学界对正铁氧体的兴趣。尽管如此，要进行这些研究，深入了解平衡条件下的晶格激发至关重要。在这项工作中，我们通过偏振拉曼光谱和红外光谱，在室温下对 NdFeO 单晶中的光学活性区中心声子进行了全面表征。该研究通过 4 K 下的偏振红外光谱和 10 K 下的非偏振拉曼散射进行补充。预测的极性声子与一些晶体场激发一起被成功观测到。第一性原理模拟进一步确定了光学声子的本征模式和对称性归属。计算得到的每个模式的原子运动具有重要意义，因为它们在所有正铁氧体以及大多数正交晶系 Pbnm 钙钛矿大家族中都是常见的。
