Effect of Chemical Pressure on the Charge Density Wave Transition in Rare-earth Tritellurides $R$Te$_3$

The charge density wave transition is investigated in the bilayer family of rare-earth tritelluride RTe{sub 3} compounds (R=Sm, Gd, Tb, Dy, Ho, Er, and Tm) via high-resolution x-ray diffraction and electrical resistivity. The transition temperature increases monotonically with increasing lattice parameter from 244(3) K for TmTe{sub 3} to 416(3) K for SmTe{sub 3}. The heaviest members of the series, R=Dy, Ho, Er, and Tm, are observed to have a second transition at a lower temperature, which marks the onset of an additional charge density wave with wave vector almost equal in magnitude to the first, but oriented in the perpendicular direction.