Dresden 2017 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 66: Poster 3
MA 66.21: Poster
Freitag, 24. März 2017, 09:30–13:00, P2-OG2
Comparative study of CoFeAlB and CoFeB FMR properties for spin torque devices — •Andres Conca1, Thomas Meyer1, Takafumi Nakano2, Yasuo Ando2, and Burkard Hillebrands1 — 1FB Physik and Landesforschungszentrum OPTIMAS, TU Kaiserslautern, Germany — 2Department of Applied Physics, Tohoku University, Japan
The magnitude of critical current required for switching in spin transfer torque (STT) devices is ruled by the product of the Gilbert damping parameter α and the square of the saturation magnetization Ms of the electrode material. Co40Fe40B20 is dominantly used as free layer electrode in MgO-based MTJs. The material has a low α around 0.0042 but the large Ms hinders the use in STT devices. In this sense, research has been carried out to dope CoFeB alloys in order to reduce the magnetization without destroying the low damping properties. Here, we present results of the FMR properties of film series of Co36Fe36Al18B10 with different annealing temperatures. The dependence of the linewidth, α, and Ms have been obtained. Additional information regarding the exchange constant is gained through measurements of the perpendicular standing spin waves (PSSW). An additional CoFeB series has also been measured for comparison. The data proves a significant reduction of Ms and the exchange constant in CoFeAlB compared to CoFeB while α remains similar or even smaller for most of the annealing temperatures. The evolution of α with annealing shows a different behavior for both materials. This proves the suitability of CoFeAlB for STT devices. Support by M-era.Net and HEUMEM is acknowledged.