First-order paramagnetic-to-commensurate phase transition in Cr alloys

The coexistence of spin- and charge-density waves in pure Cr and its dilute alloys continues to fascinate both experimentalists and theorists. Using a three-band model, we show that the charge-density wave (CDW) in incommensurate (I) Cr alloys is governed by the same Coulomb interaction that produces a first-order Néel transition in commensurate (C) alloys. Therefore, we predict that the first-order paramagnetic-to-commensurate transition observed in CrFe and CrSi alloys is preceded by the growth of a large CDW in the I phase of each alloy. We also provide a justification for the three-band model in the I phase and show that it reduces to the correct form in the C limit.