"Resonant enhancement of charge density wave diffraction in the rare-earth tritellurides"

W. S. Lee: A. P. Sorini, M. Yi, Y. D. Chuang, B. Moritz, W. L. Yang, J.-H. Chu, H. H. Kuo, A. G. Cruz Gonzalez, I. R. Fisher, Z. Hussain, T. P. Devereaux, and Z. X. Shen; Phys. Rev. B , 04/27/12.

Additional Authors: A. P. Sorini, M. Yi, Y. D. Chuang, B. Moritz, W. L. Yang, J.-H. Chu, H. H. Kuo, A. G. Cruz Gonzalez, I. R. Fisher, Z. Hussain, T. P. Devereaux, and Z. X. Shen

Abstract:

We performed resonant soft x-ray diffraction on known charge density wave (CDW) compounds, rare-earth tritellurides. Near the M5 (3d-4f) absorption edge of rare-earth ions, an intense diffraction peak is detected at a wave vector identical to that of the CDW state hosted on Te2 planes, indicating a CDW-induced modulation on the rare-earth ions. Surprisingly, the temperature dependence of the diffraction peak intensity demonstrates an exponential increase at low temperatures, vastly different than that of the CDW order parameter. Assuming 4f multiplet splitting due to the CDW states, we present a model to calculate x-ray-absorption spectrum and resonant profile of the diffraction peak, agreeing well with experimental observations. Our results demonstrate a situation where the temperature dependence of resonant x-ray-diffraction peak intensity is not directly related to the intrinsic behavior of the order parameter associated with the electronic order, but is dominated by the thermal occupancy of the valence states.