Paramagnetic complexes in beryllium-doped hexagonal boron nitride crystals

Abstract

This work is devoted to the investigation of paramagnetic centers in a single crystal of hexagonal boron nitride (h-BN) with beryllium introduced via high-temperature diffusion. Electron paramagnetic resonance (EPR) spectra and their dependence on the orientation of the magnetic field relative to the crystallographic axes and temperature were measured in hexagonal boron nitride crystals. The observed dependencies are explained by the presence of two types of paramagnetic centers. The first type consists of three exchange-interacting paramagnetic centers, each with spin S = 1/2, with g-values of g_∥ = 2.0 and g_⊥ = 2.7, which allow for the observation of lines with effective g-values of g_∥ = 6.0 ± 0.3 and g_⊥ =3.5 ± 0.2 at 16 K. The exchange coupling constant was estimated from the temperature dependence of the g-factor at 16-120 K range. The second type of centers is attributed to a defect with spin S = 1/2, exhibiting g-values of g_∥ = 2.18 ± 0.01 and g_⊥ = 2.06 ± 0.01, with a distinct orientation in the ab plane of the crystal.