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arXiv · 1708.05307

On the possibility to detect multipolar order in URu$_2$Si$_2$ by the electric quadrupolar transition of resonant elastic X-ray scattering

Y. L. Wang·G. Fabbris·D. Meyers·N. H. Sung·R. E. Baumbach·E. D. Bauer·P. J. Ryan·J. -W. Kim·X. Liu·M. P. M. Dean·G. Kotliar·X. Dai
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Abstract

Resonant elastic X-ray scattering is a powerful technique for measuring multipolar order parameters. In this paper, we theoretically and experimentally study the possibility of using this technique to detect the proposed multipolar order parameters in URu$_2$Si$_2$ at the U-$L_{3}$ edge with the electric quadrupolar transition. Based on an atomic model, we calculate the azimuthal dependence of the quadrupolar transition at the U-$L_{3}$ edge. The results illustrate the potential of this technique for distinguishing different multipolar order parameters. We then perform experiments on ultra-clean single crystals of URu$_2$Si$_2$ at the U-$L_{3}$ edge to search for the predicted signal, but do not detect any indications of multipolar moments within the experimental uncertainty. We theoretically estimate the orders of magnitude of the cross-section and the expected count rate of the quadrupolar transition and compare them to the dipolar transitions at the U-$M_4$ and U-$L_3$ edges, clarifying the difficulty in detecting higher order multipolar order parameters in URu$_2$Si$_2$ in the current experimental setup.

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Y. L. Wang, G. Fabbris, D. Meyers, N. H. Sung, R. E. Baumbach, E. D. Bauer, P. J. Ryan, J. -W. Kim, X. Liu, M. P. M. Dean, G. Kotliar, X. Dai. 2017-08-17. On the possibility to detect multipolar order in URu$_2$Si$_2$ by the electric quadrupolar transition of resonant elastic X-ray scattering. https://doi.org/10.1103/physrevb.96.085146

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