Charge density wave formation in R2 Te5 (R=Nd, Sm, and Gd)

The rare earth (R) tellurides R2 Te5 have a crystal structure intermediate between that of R Te2 and R Te3, consisting of alternating single and double Te planes sandwiched between RTe block layers. We have successfully grown single crystals of Nd2 Te5, Sm2 Te5, and Gd2 Te5 from a self-flux and we describe here evidence for charge density wave formation in these materials. The superlattice patterns for all three compounds are relatively complex, consisting at room temperature of at least two independent wave vectors. Consideration of the electronic structure indicates that, to a large extent, these wave vectors are separately associated with sheets of the Fermi surface which are principally derived from the single and double Te layers.