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Electron-Phonon coupling in Charge Density Wave ZrTe3

Moritz Hoesch - European Synchrotron Radiation Facility, Grenoble, France


The Charge Density Wave (CDW) in ZrTe3 is driven by a Fermi-surface nesting of the quasi 1-dimensional Fermi surface sheet of the Te px orbitals. The layered material is made of prismatic ZrTe6 chains that are laterally linked through Te p-bonding. The CDW develops below T_CDW = 63 K with a modulation vector q_CDW in the a*-c*-plane.

 

In this seminar I will present a elastic and inelastic x-ray scattering study of the CDW super-structure as a function of temperature and pressure and the lattice dynamics of ZrTe3 and the giant Kohn Anomaly.

 

The CDW is observed in the lattice dynamics as a dip in the acoustic transveres phonon with polarization along a* dispersing along q_CDW. The temperature dependence of the phonon softening and the diffuse scattering reveals strongly non-mean-field behaviour of the phase transition and critical exponents are derived that correspond to a two-dimensional universality class. At pressures up to 6GPa the evolution of the CDW superstructure is traced up to its disappearance. This evolution is explained by Fermi surface calculations that show the evolution of the nesting.