Ferromagnetic resonance in tunnel junctions: Mag-noise and complex impedance analysis

Autor: J. R. Childress, Valeri Synogatch, Neil Smith
Rok vydání: 2003
Předmět:
Zdroj: Journal of Applied Physics. 93:8570-8572
ISSN: 1089-7550
0021-8979
DOI: 10.1063/1.1557852
Popis: Ferromagnetic resonance (FMR) in the Co80Fe20/Ni80Fe20 free (sense) layer of micron-sized, magnetic tunnel junction (MTJ) devices is studied by two different techniques. The first method employs the MTJ device’s magnetoresistance, and measures thermally excited magnetization fluctuations (mag-noise) as a resistance noise spectrum. Correlations between magnetoresistance and FMR frequency versus in-plane magnetic field have been observed for different devices. The FMR frequencies agreed well with calculations when including substantial out-of-plane magnetic anisotropy fields. The second method detects the change in the complex impedance of the MTJ before and after applying a dc current, as measured by a vector network analyzer. The latter method seems to be very sensitive to internal nonuniform states of the free layer magnetization.
Databáze: OpenAIRE