Unusual temperature dependence of the photoluminescence emission of MgV centers in diamond

Magnesium-and germanium-vacancy centers were produced in diamond by ion implantation and the post-annealing process. Photoluminescence spectroscopy (PL) measurements were performed between 20 and 50 °C. The PL results of the GeV centers are in agreement with those found in the literature, while the MgV center is newly discovered and a not yet broadly investigated color center, but the room temperature PL results are in agreement with the first report. The temperature dependence of the MgV centers above room temperature is unusual: by increasing the temperature, its PL shifts to higher energies, contrary to what is observed for the GeV centers and other known centers in the literature. The zero phonon line width of both centers broadens by increasing the temperature in both investigated centers. The origin of the blue shift observed in the MgV centers as a confinement effect is discarded, because sample is bulk and its origin should lay on the influence of the temperature on the local static structure and the overlapping of the electronic wave functions. Our results show the ability of MgV to be used in future for thermometry. The center is bright and photostable, with a narrow full width at half maximum compared to other centers in diamond and its shift with the temperature is also larger.