The importance of shear on the collective charge transport in CDWs revealed by an XFEL source.

Charge transport in materials has an impact on a wide range of devices based on semiconductor, battery, or superconductor technology. Charge transport in sliding charge density waves (CDW) differs from all others in that the atomic lattice is directly involved in the transport process. To obtain an overall picture of the structural changes associated to the collective transport, the large coherent x-ray beam generated by an x-ray free-electron laser (XFEL) source was used.

Charge density waves tuned by biaxial tensile stress.

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 TbTe 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.

compression of micropillars under coherent X-ray diffraction: a case study of experimental and data-analysis constraints.

Micropillar compression is a method of choice to understand mechanics at small scale. It is mainly studied with electron microscopy or white-beam micro-Laue X-ray diffraction. The aim of the present article is to show the possibilities of the use of diffraction with a coherent X-ray beam.

Time-resolved structural dynamics of the out-of-equilibrium charge density wave phase transition in GdTe.

We use ultrafast electron diffraction to study the out-of-equilibrium dynamics of the charge density wave (CDW) phase transition in GdTe, a quasi-two-dimensional compound displaying a unidirectional CDW state. Experiments were conducted at different incident fluences and different initial sample temperatures below T. We find that following photo-excitation, the system undergoes a non-thermal ultrafast phase transition that occurs in out-of-equilibrium conditions.