Influence of Sample Geometry on Inductive Damping Measurement Methods

• Published in: IEEE transactions on magnetics 2011-10, Vol.47 (10), p.2502-2504
• Main Authors: Liebing, N., Serrano-Guisan, S., Caprile, A., Olivetti, E. S., Celegato, F., Pasquale, M., Muller, A., Schumacher, H. W.
• Format: Article
• Language: English
• Subjects: Coplanar waveguides; Cross-disciplinary physics: materials science; rheology; Damping; Exact sciences and technology; Ferromagnetic resonance; Frequency domain analysis; Gilbert damping; magnetic films; magnetic materials; Magnetic resonance; magnetic variables measurements; Magnetization; Magnetomechanical effects; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; nanostructured materials; Other topics in materials science; permalloy; Physics; PIMM; thin films; VNA-FMR
• ISSN: 0018-9464; 1941-0069
• DOI: 10.1109/TMAG.2011.2155637

We study the precession frequency and effective damping of patterned permalloy thin films of different geometry using integrated inductive test structures. The test structures consist of coplanar wave guides fabricated onto patterned permalloy stripes of different geometry. The width, length and position of the permalloy stripe with respect to the center conductor of the wave guide are varied. The precession frequency and effective damping of the different devices is derived by inductive measurements in time and frequency domain in in-plane magnetic fields. While the precession frequencies do not reveal a significant dependence on the sample geometry we find a decrease of the measured damping with increasing width of the permalloy centered underneath the center conductor of the coplanar wave guide. We attribute this effect to an additional damping contribution due to inhomogeneous line broadening at the edges of the permalloy stripes which does not contribute to the inductive signal provided the permalloy stripe is wider than the center conductor. Consequences for inductive determination of the effective damping using such integrated reference samples are discussed.