Density Waves in Linear Chain Compounds

Abstract

These notes are intended to give an overview of the field which, in general, is referred to as density waves in solids. In their simplest form, two types of density waves occur, they are called charge and spin density waves. Charge density waves were first discussed by Fröhlich in 1954 and by Peierls in 1955; spin density wave states were postulated by Overhauser in 1962. It was recognized early that highly anisotropic band structures are important in leading to these ground states. Experimental evidence for these ground states was found much later, when materials with a linear chain structure and with metallic properties were discovered and investigated. Several groups of both organic and inorganic materials are now standard examples of density wave ground states; some members of these groups have been investigated in detail by a wide array of experimental techniques.