Nuclear spin decoherence of neutral ³¹P donors in silicon: Effect of environmental ²⁹Si nuclei

الأصل · EN

Spectral diffusion arising from ²⁹Si nuclear spin flip-flops, known to be a primary source of electron spin decoherence in silicon, is also predicted to limit the coherence times of neutral donor nuclear spins in silicon. Here, the impact of this mechanism on ³¹P nuclear spin coherence is measured as a function of ²⁹Si concentration using X-band pulsed electron nuclear double resonance (ENDOR). The ³¹P nuclear spin echo decays show that decoherence is controlled by ²⁹Si flip-flops resulting in both fast (exponential) and slow (non-exponential) spectral diffusion processes. The decay times span a range from 100 ms in crystals containing 50% ²⁹Si to 3 s in crystals containing 1% ²⁹Si. These nuclear spin echo decay times for neutral donors are orders of magnitude longer than those reported for ionized donors in natural silicon. The electron spin of the neutral donors `protects' the donor nuclear spins by suppressing ²⁹Si flip-flops within a `frozen core', as a result of the detuning of the ²⁹Si spins caused by their hyperfine coupling to the electron spin.