Afterglow and Quantum Tunneling in Ce-Doped Lutetium Aluminum Garnet

We study the presence of quantum tunneling between the Ce
³⁺
activator and host traps in lutetium aluminum garnet (LuAG). We monitor the afterglow of several Ce
³⁺
(Mg
²⁺
)-doped LuAG samples in crystal and powder forms. The experiment is performed in the extended temperature range of 77-400 K. An inverse power-law function is fit to the data. A power-law exponent close to 1 confirms that the signal observed up to temperatures around 200-250 K is due to quantum tunneling between the Ce activators and traps.