Spin Relaxation of Impurity centers in Oxides and Semiconductors in Fields up to 14 T

The Spin Lattice Relaxation (SLR) and spin decoherence times can be a strong function of magnetic field, especially at low temperatures. These parameters are of crucial significance to possible applications like spin-based information storage or spin-based quantum information processing. However, experimental data above fields of 3 Tesla are lacking. Here we report a study of the field dependence of both SLR and decoherence times in various materials at high magnetic fields by a direct time-domain measurement of T₁ and T₂ relaxation times with pulsed electrons paramagnetic resonance (EPR) at 120, 240, 336, and 395 GHz. Below 80K for Mn²⁺, V²⁺, and Cr³⁺ impurities in MgO the SLR is strongly field dependent, and shows an approximate B² dependence, while in N-doped SiC the SLR is strongly dependent on magnetic field at temperatures below 12K with an approximate B⁴ dependence. These results are compared to theoretical and experimental phonon densities in these materials and to calculated values of the direct single-phonon spin lattice relaxation.