Magneto-optical properties of lanthanide-doped nanospinels

Matthew C. Ellis, David Hardy, Rodney Tigaa, Stephen McGill, Geoffrey F. Strouse, and Naresh Dalal

Florida State University, National High Magnetic Field Laboratory

High performance down-shifting phosphors are being developed for applications in solid-state lighting. These materials absorb higher energy photons and convert them to lower energy single photons. The use of trivalent lanthanide (Ln³⁺) ions (Ln=Eu, Tb, Er, Dy, Sm, Y, or Yb) doped into semiconductor nanoparticles allows for color-pure emission, which is currently in high demand commercially, due to the narrow emission linewidths (FHWM≈10 nm). While lanthanides have been thoroughly studied in virtually every aspect, pertaining to photophysics, few studies have been conducted on the magneto-optical properties of the 4f elements. A magnetic effect on photoluminescence (PL) emission intensity has been observed in lanthanide-doped materials and attributed to changes in site symmetry of the Eu³⁺ ion, cross-relaxation and Zeeman splitting effects. PL emission spectra collected on Ln³⁺-doped zinc aluminate (ZnAl₂O₄:Ln) and zinc gallate (ZnGa₂O₄:Ln) nanospinels in a 17.5 T superconducting magnet will be discussed to better understand the source of the observed emission quenching.