Invariant incommensurate coherence length in spin-density-wave excitation of Cr0.99Fe0.01

• Published in: Journal of magnetism and magnetic materials 2019-01, Vol.469, p.629-632
• Main Authors: Hiraka, Haruhiro, Yano, Shin-ichiro, Fukuda, Tatsuo
• Format: Article
• Language: English
• Subjects: Cr alloy; Inelastic neutron scattering; Magnetic excitation; Spin density wave; Standing wave
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2018.09.035

•A vertical dispersion appeared in the incommensurate spin-density-wave excitations of Cr0.99Fe0.01.•The dispersion could not be explained using the concept of conventional antiferromagnetic dispersion.•We newly proposed the presence of possible excitations from standing waves in local spin matrices.•In our model, the effectively vertical dispersion was attributed to the longitudinal spin fluctuation excited in local spin matrices.•A series of low-energy magnetic excitations in Cr alloys could be understood with the coexistence of standing waves and progressive waves. Low-energy magnetic excitation of spin-density wave (SDW) was measured using a single crystal of Cr0.99Fe0.01 by cold neutron triple-axis spectroscopy. Because of the unchanged incommensurate Q and the constant line width in 2.5⩽ℏω⩽6 meV, the magnetic excitation could not be explained with a conventional dispersion of ℏωq∝q. Here, we conjectured the presence of standing waves, which would be excited in local spin matrices. The effectively vertical dispersion was attributed to the longitudinal spin fluctuation in the spin matrices. A series of low-energy magnetic excitations in Cr alloys could be understood with the coexistence of the standing waves and progressive waves such as spin waves.