Electronic crystals: an experimental overview

Abstract

This article reviews the static and dynamic properties of spontaneous superstructures formed by electrons. Representations of such electronic crystals are charge density waves (CDW) and spin density waves in inorganic as well as organic low-dimensional materials. A special attention is paid to the collective effects in pinning and sliding of these superstructures, and the glassy properties at low temperature. Charge order and charge disproportionation which occur in organic materials resulting from correlation effects are analysed. Experiments under magnetic field, and more specifically field-induced CDWs are discussed. Properties of meso- and nanostructures of CDWs are also reviewed.

PACS:

• 71.45.Lr Charge density waves
• 75.30.Fv Spin density waves
• 74.70.Kn Organic superconductors
• 72.15.Nj Collective modes in one-dimension
• 71.10.Hf Non-Fermi-liquid ground states
• 75.25.Dk Orbital
• charge and other orders

Keywords:

• strongly correlated electronic systems
• metal-insulator transition
• one-dimensional conductors
• charge density wave
• spin density wave
• quantum solids
• collective modes
• Fermi surface instabilities

Acknowledgements

I acknowledge Georges Waysand for having introduced me to the physics of low-dimensional materials. I am very grateful for having worked closely with Katica Biljakovic, Roland Currat, Jean-Claude Lasjaunias, Yuri Latyshev, François Lévy, José-Emilio Lorenzo-Dias, Felix Nad, Michel Renard, Michel Saint-Paul and Alexander Sinchenko for a lasting, fruitful collaboration on the different topics of this review. I also thank many others, students, colleagues and visitors for their important contribution. I am very thoughtful of the late Madeleine Monceau who was a permanent help to me for so many years. I am deeply indebted to Danièle Devillers for her continuous, endless assistance in shaping the manuscript. Finally, I am grateful to Professor, David Sherrington, the Editor, for giving me the opportunity to write this review, and for having been so patient in waiting for its submission.