标题： 动态Jahn-Teller效应对UxTh1-xO2体系中磁激发、晶格振动和热导率的影响 显示英文标题

标题： Impact of dynamic Jahn-Teller effect on magnetic excitations, lattice vibration, and thermal conductivity in UxTh1-xO2 system

摘要： 单晶铀-钍二氧化物(UxTh1-xO2)在0<x<1的全浓度范围内的振动和磁性特性被研究。二氧化钍是一种抗磁体，其热性质由晶格振动决定。加入顺磁性的铀离子导致磁性效应的出现，即使在室温下也会显著改变热物理性质。声子与铀5f电子的磁矩通过磁弹性耦合相互作用，导致低温热导率曲线出现异常。磁化率测量的分析表明，有效磁矩的减少与铀浓度有关，这种现象之前被认为与动态Jahn-Teller(DJT)效应有关。T2g拉曼峰位置随着铀浓度的变化呈现非线性趋势，并暗示这些拉曼活性光学模式在DJT或介导四极-四极相互作用中起作用。基于第一性原理的热输运模型被用来解释低温输运测量，其中异常的减少归因于声子-自旋共振散射。使用高分辨率非弹性X射线散射(IXS)测量声子线宽，也捕捉到了自旋和声子之间的相互作用。我们的结果为声子与磁激发之间的相互作用提供了新的见解，这些相互作用支配着DJT效应并影响该材料体系中的低温热输运过程。这些发现对理解信息处理和能源应用中先进材料的低温热输运和磁性特性具有重要意义。 显示英文摘要

摘要： Vibrational and magnetic properties of single-crystal uranium-thorium dioxide (UxTh1-xO2) with a full range of 0<x<1 is investigated. Thorium dioxide is a diamagnet whose thermal properties are governed by lattice vibration. The addition of paramagnetic uranium ion leads to the emergence of magnetic effects that alter the thermophysical properties noticeably even at room temperature. The interaction of phonons with magnetic moments of uranium 5f electrons mediated by magnetoelastic coupling results in an anomalous low-temperature thermal conductivity profile. Analysis of the magnetic susceptibility measurements indicates a uranium-concentration-dependent reduction in effective magnetic moment previously associated with the dynamic Jahn-Teller (DJT) effect. The T2g Raman peak position follows a nonlinear trend as a function of uranium concentration and hints that these Raman active optical modes play a role in either DJT or mediating quadrupole-quadrupole interactions. A first principle-based thermal transport model is implemented to explain the low-temperature transport measurements, where the anomalous reduction is attributed to phonon-spin resonant scattering. The interplay between spins and phonons is also captured using high-resolution inelastic X-ray scattering (IXS) measurements of phonon linewidths. Our results provide new insights into the phonon interactions with the magnetic excitations governing DJT effect and impacting the low-temperature thermal transport processes in this material system. These findings have implications for understanding low-temperature thermal transport and magnetic properties in advanced materials for information processing and energy applications.