Upconversion emission enhancement of Gd3+ ions induced by surface plasmon field in Au@NaYF4 nanostructures codoped with Gd3+-Yb3+-Tm3+ ions

► Prepared Au nanoparticles (NPs) attached β-NaYF4 NCs by a facial solution method. ► Enhanced ultraviolet upconversion luminescence was observed in the nanostructures. ► The largest enhancement factor was obtained to be 76 for the 6IJ → 8S7/2 emission. ► The as-obtained nanostructure also exhibits paramagnetism at room temperatures.