Electron Spin-Relaxation Times of Phosphorus Donors in Silicon

TL;DR

This study investigates the temperature-dependent electron spin relaxation times in phosphorus-doped silicon, revealing the dominant relaxation mechanisms and intrinsic coherence times relevant for quantum information applications.

Contribution

It provides detailed measurements of T1 and T2 relaxation times in natural and isotopically purified silicon, highlighting the role of the Orbach process and intrinsic spin coherence.

Findings

T1 shows strong temperature dependence due to the Orbach process.

Intrinsic T2 in 28Si:P is approximately 60 ms at 7 K.

Spin decoherence is dominated by the Orbach process above ~12 K.

Abstract

Pulsed electron paramagnetic resonance measurements of donor electron spins in natural phosphorus-doped silicon (Si:P) and isotopically-purified 28Si:P show a strongly temperature-dependent longitudinal relaxation time, T1, due to an Orbach process with DeltaE = 126 K. The 2-pulse echo decay is exponential in 28Si:P, with the transverse relaxation (decoherence) time, T2, controlled by the Orbach process above ~12 K and by instantaneous diffusion at lower temperatures. Spin echo experiments with varying pulse turning angles show that the intrinsic T2 of an isolated spin in 28Si:P is ~60 ms at 7 K.