Charge- and spin-density waves observed through their spatial fluctuations by coherent and simultaneous x-ray diffraction

Abstract

Spatial fluctuations of spin-density wave (SDW) and charge-density wave (CDW) in chromium have been compared by combining coherent and simultaneous x-ray diffraction experiments. Despite their close relationship, spatial fluctuations of the spin and of the charge-density waves display a very different behavior: the satellite reflection associated to the charge density displays speckles while the spin one displays an impressive long-range order. This observation is hardly compatible with the commonly accepted magneto-elastic origin of CDW in chromium and is more consistent with a purely electronic scenario where CDW is the second harmonic of SDW. A BCS model taking into account a second-order nesting predicts correctly the existence of a CDW and explains why the CDW is more sensitive to punctual defects. © 2014 American Physical Society.