Spin-Density-Wave, Charge-Density-Wave and Stain-Wave in Chromium—Order of the Phase Transition at the Néel Temperature—

Abstract

Self-consistent formulation of the incommensurate spin-density-wave (SDW) in chromium and its alloys is made by taking into account both the second harmonic charge-density-wave and strain-wave with a simplified model system. The order of the paramagnetic to SDW phase transition is studied on the basis of the Landau expansion of free energy. It is shown that the first order transition is possible if the electron-phonon coupling is sufficiently strong. Besides, it is found to be the situation favorable for the first order transition that the density of states of the reservoir is large and that the system is in the neighborhood of the commensurate-incommensurate transition point.