Charge Density Waves Tuned by Crystal Symmetry
Résumé
The electronic orders appearing in condensed matter systems originate from the precise arrangement and nature of crystal atoms. This teneous relationship can lead to highly different phases, and drive electronic phase transitions. To explore this rich physics, we developed a new device to perform true biaxial mechanical deformation of layered materials at cryogenic temperatures, compatible with x-ray diffraction and transport measurements in the same sample. Here, using this device, we show that a slight deformation of TbTe3 can have a dramatic influence on the stabilized electronic order. We report on a Charge Density Wave (CDW) orientational transition from ⃗c to ⃗a directly driven by the a/c structural parameter, with the occurence of a tiny coexistence region near a = c, without space group change. The CDW transition temperature Tc displays a linear dependence with |a/c − 1|, without saturation under deformation while the gap saturates out of the coexistence region. This behaviour is well accounted for within a tight-binding model. Our results question the relationship between the gap and Tc in RTe3 systems. More generally, our method can be applied to many systems displaying electronic phase transitions and opens a new route towards the study of coexisting or competing electronic orders in condensed matter.
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