Field-angular anisotropy of multipolar excitations

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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.