Influence of Platinum Thin Films on the Photophysical and Quantum Properties of Near‐Surface NV Centers

Abstract Nitrogen‐vacancy (NV) centers in diamond are optically addressable spin defects with great potential for nanoscale quantum sensing. A key application of NV centers is the detection of external spins at the diamond surface. Among metals, platinum thin films – widely used in spintronics, catalysis, and electrochemistry – provide a particularly interesting system for such studies. However, the interaction between NV centers and metals is known to affect their quantum sensing capabilities. In this work, five platinum‐covered diamond samples containing shallow NVs created via nitrogen implantation with different energies (2.5–60 keV) are used to investigate the optical and quantum properties of NV ensembles beneath metal films. A substantial reduction of the photoluminescence lifetime and a pronounced decrease of the NV ⁻ population are found for NV ensembles located near the diamond‐platinum interface. As a result, optically detected magnetic resonance experiments could only be efficiently performed on diamonds implanted with at least 20 keV, where a strong increase in the T ₂ coherence time beneath the platinum thin films is observed. The study describes the various processes affecting NV centers near diamond‐platinum interfaces and provides guidance for the integration of thin metal films with near‐surface NV centers.