Nature of the triple point in chromium alloys: Mode-softening of the incommensurate spin-density wave

• Published in: Physica. B, Condensed matter Condensed matter, 1997-12, Vol.241, p.625-627
• Main Authors: Noakes, D.R, Fawcett, E, Sternlieb, B.J, Shirane, G, Jankowska-Kisielinska, J
• Format: Article
• Language: English
• Subjects: Chromium alloys; Critical behavior; Magnetic phase diagram; Triple-axis neutron scattering
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/S0921-4526(97)00663-7

The magnetic stiffness parameter, A 2, associated with the critical fluctuations in the paramagnetic phase close to the incommensurate spin-density-wave (SDW) transition of a Cr + 0.18 at% Re single crystal, when compared with that of pure chromium and dilute alloys of vanadium in chromium, indicates that the singularity responsible for the onset of the commensurate SDW phase occurs when A 2 approaches zero at a finite value of the incommensurability parameter, δ ≊ 0.017 rlu , instead of zero as usually assumed. The mode of the incommensurate SDW softens as δ approaches this critical value with rhenium doping, and conversely hardens as δ increases when vanadium is added to chromium. Also, the amplitude of the critical scattering increases as δ approaches its end point, by a factor of about two going from 0.2 and 0.5at% V to pure chromium, and by another factor near two in going from pure Cr to Cr + 0.18at%Re.