Surface Plasmon Resonance (SPR) Effect in Nanoscale Nichrome Alloy Films

We have performed surface plasmon resonance (SPR) experiments at 633 nm in the Kretchmann configuration on prisms coated with single metal and Nichrome alloy thin films of ~ 500 Aring. The thin films used in this study are grown by magnetron sputtering, and are binary alloy films (Nickel/Chrome with 80/20 concentration). In addition, for comparison we will also present results for pure metal films (Nickel and Chromium). We have observed a pronounced SPR signal at 633 nm for the Nichrome film while neither of the metal thin films (Ni or Cr) yields an SPR effect. We have grown companion layers of Nichrome, Nickel, and Chromium and investigated their dielectric function in the wavelength range 400 -900 nm. The resulting value of the dielectric function is used to model the reflectance from the prism/metal interface.