Concentration Dependence of the Spin-Density-Wave Periodicity in Antiferromagnetic Chromium Alloys

Abstract

The dependence of the periodicity of the spin-density waves in antiferromagnetic metals upon the number of conduction electrons is studied theoretically. It is seen that the commensurable structure, i.e., the structure for which the wave vector q equals half a reciprocal lattice vector G, is the state of minimum energy over a finite range of electron densities. The effect, which has been observed experimentally, is essentially due to the presence of two energy gaps which coalesce into one in the commensurable state. The theory gives quantitative relationships which are in good agreement with the experimentally determined values for the chromium-rich Cr-Mn and Cr-Re alloys.