Low spin current-driven dynamic excitations and metastabilityin spin-valve nanocontacts with unpinned artificial antiferromagnet

• Published in: Applied physics letters Vol. 98; no. 4; pp. 042504 - 042504-3
• Main Authors: Eggeling, M., Dimopoulos, T., Uhrmann, T., Bethge, O., Heer, R., Höink, V., Brückl, H.
• Format: Journal Article
• Published: American Institute of Physics 24-01-2011
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.3537953

This work investigates the spin-torque-related dynamics of nonuniform magnetic vortexlike states in spin-valve nanocontacts, employing an unpinned artificial antiferromagnet as polarizer and amorphous
Co
Fe
B
as free layer. Subgigahertz spectra are obtained for contacts of 150-200 nm in diameter. Low critical current density and reversibility of the dynamic spectra with respect to the current are obtained. The spectral power and linewidth depend on the in-plane magnetic field, assuming maximum, respectively minimum, values within the free layer's magnetization switching. For certain field and current windows metastable dynamic states are clearly demonstrated.