Charge density wave in layered La1 -xCexSb2

The layered rare-earth diantimonides R Sb₂ are anisotropic metals with generally low electronic densities whose properties can be modified by substituting the rare earth. LaSb₂ is a nonmagnetic metal with a low residual resistivity presenting a low-temperature magnetoresistance that does not saturate with the magnetic field. It has been proposed that the latter can be associated to a charge density wave (CDW), but no CDW has yet been found. Here we find a kink in the resistivity above room temperature in LaSb₂ (at 355 K) and show that the kink becomes much more pronounced with substitution of La by Ce along the La_{1 -x}Ce_xSb₂ series. We find signatures of a CDW in x-ray scattering, specific heat, and scanning tunneling microscopy (STM) experiments in particular for x ≈0.5 . We observe a distortion of rare-earth-Sb bonds lying in-plane of the tetragonal crystal using x-ray scattering, an anomaly in the specific heat at the same temperature as the kink in resistivity and charge modulations in STM. We conclude that LaSb₂ has a CDW which is stabilized in the La_{1 -x}Ce_xSb₂ series due to substitutional disorder.