发表机构
Utrecht University; University of Twente; Helmholtz Zentrum Berlin; Diamond Light Source; Institute of Mineralogy Physics of Materials（乌得勒支大学; 特温特大学; 柏林亥姆霍兹中心; 钻石光源; 矿物学与材料物理研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过RIXS实验与理论计算，揭示LaCrO3中多磁振子激发虽无色散但由传播的磁振子构成，并证明热布居可暴露其传播组分，为探测磁振子相互作用提供新方法。
AI 中文摘要
激发的色散关系通常被用来推断其微观特性：色散模式与传播相关，而非色散特征常被解释为局域化。对于复合激发，这种区分变得不那么直接，因为即使复合激发由传播的准粒子构成，其谱峰仍可保持几乎无色散。在此，我们利用动量依赖和温度依赖的共振非弹性X射线散射（RIXS）来揭示反铁磁LaCrO$_3$中多磁振子激发的起源。单磁振子强烈色散，而双磁振子和三磁振子特征则几乎保持平坦。在接近奈尔温度时，磁振子带的热布居产生反斯托克斯分支，并开辟了一个额外的三磁振子通道，涉及两个磁振子的产生和一个磁振子的湮灭。其能量和动量依赖关系可通过热加权多磁振子联合态密度计算来重现。这些结果确立了热布居作为一种手段，用以揭示隐藏在无色散复合激发中的传播组分，并将RIXS定位为探测多磁振子动力学以及最终磁振子-磁振子相互作用的探针。
英文摘要
The dispersion of an excitation is commonly used to infer its microscopic character: dispersive modes are associated with propagation, whereas nondispersive features are often interpreted as localized. This distinction becomes less straightforward for composite excitations, whose spectral maxima can remain nearly dispersionless even when they are built from propagating quasiparticles. Here we use momentum- and temperature-dependent resonant inelastic X-ray scattering (RIXS) to reveal the origin of multimagnon excitations in antiferromagnetic LaCrO$_3$. Whereas the single magnon disperses strongly, the two- and three-magnon features remain nearly flat. On approaching the Neel temperature, thermal population of the magnon band produces an anti-Stokes branch and opens an additional three-magnon channel involving the creation of two magnons and annihilation of one. Its energy and momentum dependence are reproduced by a thermally weighted multimagnon joint density of states calculations. These results establish thermal population as a means of exposing the propagating constituents hidden within nondispersive composite excitations, and position RIXS as a probe of multimagnon dynamics and, ultimately, magnon-magnon interactions.
