Surface plasmon excitation on magnetoactive materials

A systematic study of the excitation of surface plasmons on ferromagnetic materials in multilayered structures composed of thin films of nickel, iron, and cobalt capped by a silver layer is presented. Electromagnetic properties of the systems are theoretically and experimentally investigated as a function of the metal layers’ thickness. The critical parameters in this study of the interaction between surface plasmon waves and the magnetoactive material are discussed and an optimized structure for the investigations of spin-plasmonic effects is proposed.

Figure 1

(Color online) Reflectivity spectra obtained with $p$-polarized illumination and normalized to the baseline of 10 nm Ni [(a) solid line], Fe [(b) long dash line], and Co [(c) short dash line] films capped with a 40 nm Ag layer.

Figure 2

(Color online) (a) Reflectivity spectra obtained with $p$-polarized illumination and normalized to the baseline of $\text{Ni}\left(z\right)/\text{Ag}\left(50\text{nm-}z\right)$ samples, where $z$ is the layer thickness in nm (spectrum 1: solid line corresponds to $z=10\text{nm}$; spectrum 2: long dash line to $z=20\text{nm}$; spectrum 3: short dash/long dash line to $z=30\text{nm}$; and spectrum 4: short dash line to $z=40\text{nm}$). (b) Simulation of the reflectivity spectra presented in panel (a).

Figure 3

(Color online) Experimental absorption percentage (full symbols) and full width at half maximum (open symbols) of the reflectivity spectra for Co, Fe, and $\text{Ni}\left(z\right)/\text{Ag}\left(50\text{nm-}z\right)$ samples, after normalization to the baseline.

Figure 4

(Color online) Top left: Schematic view (not to scale) of the system. Top right: Magnetic-field intensity, along the $y$ axis, measured on the Ni(20 nm)/Ag(30 nm) sample at a distance of 1 mm from the surface (the sample lies between $y=0.5$ and 2.0 mm). Bottom: Normalized square modulus of the electric-field component along the growth axis $z$, for $\text{Ni}\left(z\right)/\text{Ag}\left(50\text{nm-}z\right)$ samples (1 corresponds to $z=10\text{nm}$, 2 to $z=20\text{nm}$, 3 to $z=30\text{nm}$, and 4 to $z=40\text{nm}$), in the ferromagnetic layer (full symbols) and in the Ag layer (open symbols). The dot-dashed line gives the value of the integral of the square modulus of the $z$-electric-field component over the ferromagnetic layer of thickness $z$.