Neodymium defect engineering in diamond: Unlocking dual emission and phonon-assisted energy transfer

Abstract

Neodymium (Nd)-related color centers in diamond exhibit unique photophysical properties and energy transfer dynamics, offering potential applications in quantum technologies and optoelectronics. This study investigates the formation and characteristics of Nd-related defects in type Ib and IIa diamond substrates through ion implantation and high-temperature annealing. Photoluminescence (PL) spectroscopy reveals distinct emission peaks at 556.8 and 598 nm, attributed to Nd2+ and Nd3+ states, respectively. Time-resolved measurements show significantly different lifetimes for these emissions (67.3 ns for Nd2+ and 127.1 ms for Nd3+), suggesting distinct electronic origins. Temperature-dependent PL analysis and thermal softening parameters indicate that the 556.8 nm emission arises from Nd-related vacancy-type defects. Furthermore, phonon-assisted energy transfer from Nd2+ to nitrogen-vacancy (NV−) centers is observed, with efficiency dependent on NV− concentration and temperature. First-principles calculations identify the positively charged Nd2V+ complex as the most stable defect configuration. These findings provide insights into the atomic-scale mechanisms of Nd-related color centers and their interactions with NV−, paving the way for tailored defect engineering in diamond-based quantum systems.