Non-Kramers iron S=2 ions in β-Ga2O3 crystals: High-frequency low-temperature EPR study

Using high-frequency electron paramagnetic resonance (EPR), we have observed non-Kramers ions with giant fine structure splitting of the order of 100GHz in n-type beta-Ga2O3 crystals. These EPR spectra were assigned to Fe2+ ions D-5 (3d(6)) with S=2. This interpretation was supported by experiments on Fermi level displacement induced by high-energy electron irradiation and photoexcitation of irradiated samples with 405-nm laser light. The values and signs of the basic parameters of the spin Hamiltonian for ions, namely Cr3+ (S=3/2) and Fe3+ (S=5/2), were identified, and the order of their spin levels was established.

Automated summary

Using high-frequency electron paramagnetic resonance (EPR), giant fine structure splitting of non-Kramers ions in β-Ga2O3 crystals was observed, revealing the D-5 state of Fe2+ ions. This interpretation was supported by experimental evidence.