8. Charge-Density Waves

Abstract

Publisher Summary This chapter discusses the series of scanning tunneling microscopy (STM) experiments and conclusively establishes the value of the STM in detecting the real space arrangement and the intensity of charge-density wave structure. Both the atomic and charge density wave (CDW) structure have been well resolved and the STM amplitude response has shown a systematic correlation with the strength of the CDW. CDW structure, deduced from other types of experiments, has been confirmed on an atomic scale in the real space images and in a number of cases new and unexpected results on CDW structure have been obtained. The chapter discusses that the initial AFM experiments also demonstrate that the atomic force microscope (AFM) can give good resolution of CDW structure, although the amplitude relative to the atomic amplitude is much smaller than observed with the STM. Combined STM and AFM studies should be complimentary. A large series of spectroscopy measurements have shown that reliable information on CDW energy gaps can also be obtained with the STM. The spectroscopy mode is highly sensitive, but systematic reproducibility has been obtained. The STM can be expected to supply extremely valuable information on many aspects of electronic structure in materials.