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Temperature Dependence of the FMR Linewidth in Single Crystal Ni Platelets

1973; American Institute of Physics; Linguagem: Inglês

10.1063/1.2946783

1935-0465

G. C. Bailey, C. Vittoria, Hugh C. Wolfe, C. D. Graham, J. J. Rhyne,

Metallic Glasses and Amorphous Alloys

We have measured the in‐plane ferromagnetic resonance linewidth, ΔH, and field, H, of pure nickel single crystal platelets as a function of temperature, T, from 77° to 293°K. The frequency was 9.44 GHz. At each temperature, the sample was rotated in its plane, {100}, and ΔH and H were measured as a function of the angle, α, between the applied field and the 〈100〉 direction. Of the tested samples, there are two gross effects: (1) There is an increased linewidth broadening at α = 15° from the 〈100〉 axis. This maximum in the linewidth is a factor of three larger than the linewidth along the 〈100〉 and 〈110〉 axes at 171°K. At room temperature this increase in linewidth is small. (2) At all temperatures the linewidth along the 〈100〉 axis is greater than the 〈110〉 linewidth. The difference in linewidth between these two directions increases with decreasing temperatures. The largest observed difference in linewidth is 147 Oe (ΔH110 = 307 Oe). These measurements are in general agreement with our exchange‐conductivity calculations which include crystalline magnetic anisotropy. According to our model, the large increase in linewidth is due to a "mechanical" rotation of the magnetization as the field is swept through resonance for directions away from the 〈100〉 and 〈110〉 axis.