Infrared and Raman Study of the Charge-Density-Wave Ground State

2. Infrared and Raman Study of the Charge-Density-Wave Ground State Leonardo Degiorgi Laboratorium für Festkörperphysik ETH Zürich, Switzerland

3. Organic Bechgaard Salts DNA High-Tc Cuprates Transition-Metal Trichalcogenides Carbon NT MoS2 NT One-Dimensional Quantum-Wires and Low-Dimensional Solids

4. Motivation ➠ Charge ordering in low dimensions (CDW, stripes, checkerboard) ➠ Impact of charge ordering on the lattice dynamics ➠ Interplay between electronic and phononic degrees of freedom ➠ Role played by the electron-phonon coupling ➠ Fermi surface instabilities (nesting)

5. Peierls Transition Peierls, "Quantum Theory of Solids", Oxford (1995)

6. t Fermi Surface Nesting 1-Dimensional Quasi 1-Dimensional 2-Dimensional

7. RTe3 RTe2 R2Te5 The Rare-Earth Tellurides RTen (n=2, 2.5 and 3) DiMasi et al., Phys. Rev. B52, 14516 (1995)

8. DC Transport Properties of RTe3 La, Ce, Nd, Sm, Gd, Tb and Dy Ru et al., Phys. Rev. B77, 035114 (2008)

9. Kramers-Kronig 1() (cm)-1 Photon Energy (eV) Photon Energy (eV) Reflectivity and Optical Conductivity http://www.solidphys.ethz.ch/spectro/

10. Optical Reflectivity of RTe3 Sacchetti et al., Phys. Rev. B74, 125115 (2006)

11. Plasma Frequency and Single Particle Peak in RTe3 Sacchetti et al., Phys. Rev. B74, 125115 (2006)

12. Pressure Dependence of R() in CeTe3 Lavagnini et al., Phys. Rev. B79, 075117 (2009)

13. X-ray experiment at ESRF X-Ray Diffraction Experiment

14. CDW Gap: Applied versus Chemical Pressure Dependence Sacchetti et al., Phys. Rev. Lett. 98, 026401 (2007)

15. Fermi Surface Gapping versus Single Particle Peak

16. non-interacting electron gas interacting electron gas marginal (Luttinger) liquid Fermi versus Tomonaga Luttinger Liquid 3D to 1 D Dimensionality Crossover Jerome and Schulz, Adv. Phys. 31, 299 (1982)

17. s(w)~w-1.3 Spin-Peierls Superconductor Power Law Behaviour in the Optical Conductivity of Linear Chain Bechgaard Salts (TMTTF)2X and (TMTSF)2X Conductor Insulator Spin-Density-Wave Vescoli et al., Science 281, 1181 (1998)

18. Power-Law Behaviour in 1() of RTe3 Umklapp scattering: 4K-5 Sacchetti et al., Phys. Rev. B74, 125115 (2006)

19. Power-Law Behavior of the Optical Conductivity

20. Coupled One-Dimensional Chains in High Temperature Superconductors (YBa2Cu3Oy) Y.-S. Lee et al, Phys. Rev. Lett. 94, 137004 (2005)

21. Ek ħω ħω’ E2 E1 ħω ħω’ E2 E1 Stokes Anti-Stokes Raman Scattering

22. Raman Scattering in RTe3:Chemical versus Applied Pressure Lavagnini et al., Phys. Rev. B78, 201101(R) (2008)

23. Order Parameter versus Integrated Intensity of the Raman Modes in RTe3 Petzelt and Dvorak, J. Phys. C9, 1571 (1976)

24. Conclusions and Future Outlook Tomonaga-Luttinger Liquid Phonon Dispersion and Kohn Anomaly Equivalence between Chemical and Applied Pressure Fermi Surface Gapping

25. Pressure Dependence of the CDW Gap like a BCS Order Parameter What is next? in progress

26. Lavagnini Pfuner Sacchetti Acknowledgements Experiment: A. Perucchi E. Arcangeletti L. Baldassarre M. Baldini D. Di Castro P. Postorino S. Lupi (University La Sapienza Rome and ELETTRA Trieste) M. Hanfland M. Merlini (ESRF Grenoble) Samples: I.R. Fisher N. Ru Y.K. Shin J.-H. Chu (Stanford University) Theory: T. Giamarchi (University of Geneva) R. Monnier (ETH Zurich) B. Delley (PSI)

27. Thank You for Your Attention

29. Optical Conductivity of RTe3 Sacchetti et al., Phys. Rev. B74, 125115 (2006)

30. Fraction of Ungapped Fermi Surface in RTe3 Sacchetti et al., Phys. Rev. B74, 125115 (2006)

31. E D/T s r e k 4n2Kr-5 w w T D 3 w 4n2Kr-3 D~d/D 2D T Dynamics and Transport for the Mott-Hubbard Model in One-Dimension Giamarchi, Physica B230-232, 975 (1997)

32. Raman Active Phonon Modes in RTe3 4B1g+4A1g+4B3g

33. Kohn Anomaly Phonon Dispersion in RTe3: the Kohn Anomaly A1g ➜ A1 and B1