Field-angular anisotropy of multipolar excitations

表征f电子系统多极有序的一种可能的方法是观察外加磁场中的磁激发谱，它带有多极相互作用的印记和色散关系中隐藏的有序参数。使用特定的候选模型，计算了给定场的色散，并与非弹性中子散射测量的色散进行了比较。这种方法在分析多极磁激发以及获得关于隐序对称性和不同多极之间相互作用的定量信息方面存在一些缺点和一些技术限制。在这个项目中，我提议建立一种新的范式来测量重费米子化合物CeB6中的多极激发。为了更好地进行理论和实验的比较，有必要保持动量传递不变，改变场强和场向。为了使这种测量有效，我们计划建造我们自己的机械旋转器，与中子散射实验中使用的样品环境兼容。这样的旋转体将有助于场角模式各向异性的测量，从而提高我们对场感应磁激励物理的理解。用旋转器的测量将使我们能够补充现有的关于CeB6的数据，这些数据是在沿几个高对称性的晶体方向施加的磁场下在区域中心获得的，以及多极激发对连续场旋转的依赖关系，并将这些结果与理论预测的多极激发的各向异性图进行比较。一旦生长出不同生长轴的附加晶体，就可以在倒易空间的不同高对称点获得这样的测量结果，这提供了任何其他实验方法不可能获得的信息。这些结果可以用来为理论合作者提供有关多极激发的定性新信息，从而加强目前各小组正在积极发展的确定f电子系统中各种多极之间微观相互作用参数的方法。

One possible method for characterizing multipolar order in f-electron systems is to look at the magnetic excitation spectrum in an applied magnetic field, which bears the imprint of the multipolar interactions and the hidden order parameter in its dispersion relations. Using a specific candidate model, the dispersion for a given field is calculated and then compared to that measured with inelastic neutron scattering. Such an approach suffers from several shortcomings as well as some technical restrictions in the analysis of multipolar magnetic excitations and the possibility to obtain quantitative information about hidden-order symmetry and interactions between different multipoles. In this project I propose to establish a new paradigm to measure multipolar excitations in heavy fermion compound CeB6. In order to have a better comparison between the theory and experiment, it is worthwhile to keep the momentum transfer fixed and vary the field strength and field direction. For such measurements to be effective, we plan to build our own mechanical rotator compatible with the sample environment used in neutron scattering experiments. Such a rotator would facilitate the measurements of field-angular mode anisotropies and consequently improve our understanding of the physics of field-induced magnetic excitations. Measurements with the rotator will allow us to supplement the existing data on CeB6, obtained at the zone center with the magnetic field applied along several high-symmetry crystallographic directions, with the dependence of multipolar excitations on continuous field rotation and compare these results with the theoretically predicted polar anisotropy plots of multipolar excitations. As soon as additional crystals with different growth axes are grown, such measurements can be also obtained at different high-symmetry points of reciprocal space, which provides information that is impossible to obtain by any other experimental method. The results can be used to supply qualitatively new information about multipolar excitations to the theory collaborators and thereby enhance the methodology of determining microscopic interaction parameters between various multipoles in f-electron systems that is now being actively developed by various groups.