Charge density waves tuned by biaxial tensile stress

Abstract

The precise arrangement and nature of atoms drive electronic phase transitions in condensed matter. To explore this tenuous link, we developed a true biaxial mechanical deformation device working at cryogenic temperatures, compatible with x-ray diffraction and transport measurements, well adapted to layered samples. Here we show that a slight deformation of TbTe₃ can have a dramatic influence on its Charge Density Wave (CDW), with an orientational transition from c to a driven by the a/c parameter, a tiny coexistence region near a = c, and without space group change. The CDW transition temperature T_c displays a linear dependence with $∣a/c-1∣$ 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 gap and T_c in RTe₃ systems. This method opens a new route towards the study of coexisting or competing electronic orders in condensed matter.

Previous studies of the effects of strain on charge density waves have mostly focused on uniaxial strain. Here the authors use a biaxial-strain device to demonstrate switching of the charge density wave orientation, as well as a strong linear increase of the transition temperature while the gap seems to saturate.