Ghost surface polaritons in Ca-intercalated α-vanadium pentoxide

We have examined the conditions required for the existence of ghost surface polaritons (GSPs) with oscillations and attenuation properties in a low-symmetrical α-V₂O₅ crystal in the three special geometries, where the two principal axes are situated off the surface of the crystal and the other is parallel to the surface. It is discovered that GSPs, which are made up of two coherent evanescent branch waves, can be observed in the three reststrahlen frequency bands once an angle exists between the crystal axis and the coordinate axis. The underlying mechanism governing the modulation of GSPs propagation characteristics has been explored following the intercalation of calcium (Ca) atoms into α-V₂O₅ crystals. The investigation demonstrates that Ca-intercalation can dramatically alter the main characteristics of GSPs, particularly in terms of the frequency response behavior and propagation modes. As proven by attenuated total reflection spectra, the GSPs produced in α-V₂O₅ or α'-(Ca)V₂O₅ crystal can be detectable by selecting the appropriate observation conditions, such as the gap between the prism and the crystal. The findings provide innovative insights for developing advanced optoelectronic materials and devices.