AI 中文总结
本研究通过多种实验手段探究TbFeO$_3$，发现其存在负热膨胀、自旋-声子耦合等现象，揭示该体系晶格动力学、自旋关联与磁-晶格异常间的显著相互作用。
AI 中文摘要
我们利用X射线衍射、直流磁化和拉曼散射，并辅以室温X射线光电子能谱，对正交铁氧体TbFeO$_3$开展了温度依赖的研究。X射线衍射结果显示，在5-300 K范围内存在负热膨胀，且未发生任何结构相变的情况下，冷却时晶胞体积会出现微小但系统的增大。拉曼散射测量确定了拉曼活性声子模式，且这些模式与传统Klemens非谐衰减模型存在明显偏差，尤其是声子频率方面，表明存在自旋-声子耦合。两个具有$A_g$和$B_{1g}$对称性的模式，其线形从低温下的高斯主导型转变为高温下的高斯-洛伦兹混合型，反映出从非均匀展宽到寿命驱动动力学的转变。高能拉曼光谱揭示了与Fe亚晶格相关的双磁振子激发，这与线性自旋波理论一致，其光谱权重仅表现出微弱的温度依赖性。此外，在~175 K以下出现的宽拉曼模式呈现出序参量样的温度演化，且与声子异常的起始相重合，而双磁振子响应中未观察到相应的强异常。综上，这些结果证实TbFeO$_3$是一个晶格动力学、自旋关联与涌现的局域磁-晶格异常之间存在显著相互作用的体系。
英文摘要
We report a temperature-dependent investigation of orthoferrite TbFeO$_3$ using x-ray diffraction, DC magnetization, and Raman scattering, complemented by room-temperature x-ray photoelectron spectroscopy. X-ray diffraction reveals negative thermal expansion over 5-300 K, with a small but systematic increase in unit-cell volume upon cooling in the absence of any structural phase transition. Raman scattering measurements identify the Raman-active phonon modes and show clear deviations from the conventional Klemens anharmonic decay model, particularly in phonon frequencies, indicating the presence of spin-phonon coupling. Two modes of $A_g$ and $B_{1g}$ symmetry exhibit a crossover from Gaussian-dominated line shapes at low temperatures to mixed Gaussian-Lorentzian profiles at higher temperatures, reflecting a transition from inhomogeneous broadening to lifetime-driven dynamics. High-energy Raman spectra reveal two-magnon excitations associated with the Fe sublattice, consistent with linear spin-wave theory, whose spectral weight shows only weak temperature dependence. In addition, a broad Raman mode emerging below $\sim 175$ K exhibits an order-parameter-like temperature evolution and coincides with the onset of phonon anomalies, while no corresponding strong anomaly is observed in the two-magnon response. Taken together, these results establish TbFeO$_3$ as a system with pronounced interplay among lattice dynamics, spin correlations, and emergent local magnetic-lattice anomalies.
Comments22 pages, 19 figures
