Hyperfine Interactions and Coherent Spin Dynamics of Isotopically Purified 167Er3+ in Polycrystalline Y2O3

167Er3+ doped solids are a promising platform for quantum technology due to erbium’s telecom C-band optical transition and its long hyperfine coherence times. We experimentally study the spin Hamiltonian and dynamics of 167Er3+ spins in Y2O3 using electron paramagnetic resonance (EPR) spectroscopy. The anisotropic electron Zeeman, hyperfine and nuclear quadrupole matrices are fitted using data obtained by X-band (9.5 GHz) EPR spectroscopy. We perform pulsed EPR spectroscopy to measure spin relaxation time T1 and coherence time T2 for the 3 principal axes of an anisotropic g tensor. Long electronic spin coherence time up to 24.4 μs is measured for lowest g transition at 4 K, exceeding previously reported values at much lower temperatures. Measurements of decoherence mechanism indicates T2 limited by spectral diffusion and instantaneous diffusion. Long spin coherence times, along with a strong anisotropic hyperfine interaction makes 167Er3+:Y2O3 a rich system and an excellent candidate for spin-based quantum technologies.