Measuring spin wave resonance in Ni100-xFex films: compositional and temperature dependence

• We study the composition and temperature dependence of the spin wave resonance in Ni100-xFex films, where, x is 40% or below, with a thickness of 100 nm using a temperature variable broadband ferromagnetic resonance (FMR) spectroscopy. From the uniform FMR mode, the saturation magnetization (M-s) and the Gilbert damping (alpha) are measured, and using the first perpendicular standing spin wave mode, the exchange stiffness constant (A) is determined. At lower temperatures, we measure an increase of both M-s and A, while alpha shows a very weak temperature dependence. We find that M-s follows perfectly Bloch's law, while A is best described by a T-2 law. Additionally, we measure a linear increase in M-s and A with the increase of Fe content in films, while a strongly decreases. The compositional variation of alpha and A can be ascribed to the increase of M-s in Fe-rich films. Furthermore, we estimate the exchange length (L-ex) in Ni100-xFex films. We find that Lex is temperature independent, however, a strong decrease of L-ex is measured in Fe-rich films. This reduction is inversely proportional to root M-s.

Ämnesord

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

Nyckelord

spin wave resonance

exchange stiffness

Ni-Fe alloys

magnetization

dynamics

exchange length

magnetization

iron

Physics

spin wave resonance

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