Spin Echo Studies On Fe3+ Ions In Gan: Spin-Phonon Relaxation And Ligand Hyperfine Interactions

The electron spin echo detected inversion recovery technique at the Q-band frequency was used to characterize spin diffusion effects in spin-lattice relaxation of compensating Fe3+ impurities in n-type doped GaN crystals. It was found that the selective saturation can be achieved in the GaN:Fe3+ system due to magnetization transfer based on the spin flip-flop cross-relaxation processes. The temperature dependence of 1/T-1 can be explained by direct spin-phonon processes (similar to T) below 25K and by Raman two-phonon processes (similar to T-9) at higher temperatures. Spin diffusion in this system is characterized by an additional cross-relaxation rate which is weakly temperature-dependent below 25K. The transferred hyperfine interactions of Fe3+ centers with gallium and nitrogen neighbor nuclei were resolved using pulsed-electron nuclear double resonance. A comparative analysis of quadrupole interactions indicates the essential increase in the electric field gradients on the nearest nitrogen and gallium shells. Published under license by AIP Publishing.