Disorder Induced Suppression of CDW Long Range Order: STM Study of Pd-intercalated ErTe3

Pd-intercalated ErTe3 is studied as a model system for the interplay between a bidirectional two component charge density wave (CDW) state and disorder. Using scanning tunneling microscopy (STM), we show that introducing Pd-intercalants (i.e. disorder) disrupts the long-range order of both CDW states via the creation of dislocations, which appear associated with each CDW separately. While for weak disorder both CDW states continue to coexist throughout the sample, with no "domains" of one CDW direction or another, increasing Pd concentration has a stronger effect on the secondary CDW state, manifested in higher density of dislocations. Vestiges of the two distinct CDW phases persist to intercalation levels much above where signatures of the original phase transition are totally suppressed. This study therefore presents a first look into the disruption of multiple 2D strong-coupling CDW states by the proliferation of dislocations.