Disorder-induced suppression of charge density wave order: STM study of Pd-intercalated ErTe3

Abstract

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. arXiv:1901.03471v2 [cond-mat.str-el]

Suppression of charge density wave order by disorder in Pd-intercalated ErTe3

“…For these intermediate dopings (and possibly larger dopings at lower temperatures) the existence of peaks in the presence of disorder may signify the existence of a Bragg glass phase 46 , which is characterized by quasi-long-range order as well as a lack of unpaired dislocations. Such a phase has been reported in other CDW systems 47 , and indeed recent STM measurements on crystals of Pd x ErTe 3 reveal possible signatures of such a state 48 . Further high-resolution xray di↵raction studies are required to definitively establish this.…”

“…at 30 K. The intensity of the peak at the secondary CDW wavevector grows more slowly and the temperature dependence of the width levels of at approximately 90 K. Similar conclusions have recently been reached by STM measurements of Pd x ErTe 3 . 48 Previous measurements on pristine ErTe 3 25 have demonstrated that the integrated intensity of the peak The secondary CDW peaks show up weakly, and are strongest near the four Bragg peaks in the corner rather than the peak centered here. This is simply due to the structure factor of the material.…”

Nonequilibrium charge-density-wave order beyond the thermal limit

“…In the overshoot regime, after dampening of the initial oscillations, the order parameter can get trapped at the metastable local maximum despite an incipient recovery of the double-well ground state. However, in real systems, several microscopic processes, such as local modification of T c by crystal defects 54 , 55 , CDW nucleation and creation of topological defects 47 and coupling of the collective excitation to other phonons 36 , will screen against a pronounced critical slowing-down. However, such effects go beyond our current model.…”

Evidence for realignment of the charge density wave state in ErTe$_3$ and TmTe$_3$ under uniaxial stress via elastocaloric and elastoresistivity measurements

“…Reproducing the proper topology of the phase diagram for the heavy rare earth compounds requires the inclusion of higher order terms. One such model has been explored to 8th order for the case of RTe 3 in the presence of disorder [34]. In the pristine case, we have found that adding the two possible sixth order terms Eq.…”