Magnetic phase diagram for spin-density waves in thin epitaxial Cr(001) films

• Published in: Journal of magnetism and magnetic materials Vol. 183; no. 1-2; pp. 5 - 18
• Main Authors: SONNTAG, P, BÖDEKER, P, SCHREYER, A, ZABEL, H, HAMACHER, K, KAISER, H
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Science 01-03-1998
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Magnetic properties and materials; Magnetic properties of monolayers and thin films; Magnetic properties of surface, thin films and multilayers; Magnetically ordered materials: other intrinsic properties; Metals. Metallurgy; Physics; Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.); Spin-density waves; Epitaxial layers; Neutron diffraction; Transition elements; Chromium; Magnetic-phase diagrams; Magnetic structure; XRD; Experimental study; Spin density waves
• ISSN: 0304-8853
• DOI: 10.1016/s0304-8853(97)01056-1

We have investigated the magnetic structure of thin [001] oriented Cr films using neutron and x-ray diffraction experiments to measure their spin density waves and the strain waves, respectively. For epitaxial Cr films with thicknesses between 1000-4000A grown on Nb films on sapphire substrates, we provide phase diagrams including incommensurate transverse and longitudinal spin-density waves (SDW) and commensurate antiferromagnetic spin structures. The results show that for Cr(001) on Nb a single domain SDW prevails with a wave vector Q perpendicular to the surface. At low temperatures the SDW is longitudinal and becomes mostly transverse between 150-250K, higher than in bulk Cr where the spin-flip transition occurs at 123K. Furthermore, the magnitude of Q is increased as compared to bulk Cr. These effects decrease with increasing film thickness. With neutron scattering we have also observed a commensurate antiferromagnetic phase with spins pointing out of the plane. The commensurate phase occurs at a temperature between 250-305K and persists up to at least 340K, far above the bulk Neel temperature of 311K for the incommensurate phase.