Density of states in chromium alloys

Both the spin- and charge-density waves of Cr alloys have significant effects on the joint density-of-states ρ(ω) of the nested electron and hole Fermi surfaces below the Néel temperature (Formula presented). The random-phase approximation is used to evaluate ρ(ω) within a three-band model of Cr alloys. In the commensurate phase of the spin-density wave, ρ(ω) contains a single energy gap 2Δ. At zero temperature, 2Δ reaches a maximum value of about 370 meV and spans the Fermi energy, which is shifted upwards by the presence of a charge-density wave (CDW). In the incommensurate phase, ρ(ω) contains two energy gaps (Formula presented) and (Formula presented) above and below midgap states. If the CDW order parameter δ vanishes, then (Formula presented)=(Formula presented) and both reach a maximum of about 130 meV at T=0; if δ is nonzero, then (Formula presented)<(Formula presented). A third energy gap (Formula presented) includes both the midgap states as well as the smaller gaps (Formula presented) and (Formula presented). For pure Cr, (Formula presented) reaches a maximum value of about 450 meV at T=0. Unlike (Formula presented) and (Formula presented), (Formula presented) does not vanish at (Formula presented) but decreases to about 370 meV. Our results are compared with those obtained earlier from a two-band model in the absence of the CDW. This paper also clarifies the assumptions made by the three-band model and the role of the unpaired holes which reside on the larger of the two nested Fermi surfaces.