29Si Nuclear-Spin Decoherence Process Directly Observed by Multiple Spin-Echoes for Pure and Carrier-less Silicon

TL;DR

This study directly measures the 29Si nuclear-spin decoherence times in pure, carrier-less silicon at room temperature using multiple spin-echoes, revealing a bi-exponential decay pattern with two distinct T2 components.

Contribution

It provides the first direct observation of 29Si nuclear-spin decoherence in pure silicon using multiple spin-echoes, highlighting a bi-exponential decay process.

Findings

Decoherence times T2S = 15 ms and T2L = 200 ms identified

Decoherence process deviates from simple Gaussian or Lorentzian models

Successful observation despite long T1 relaxation time

Abstract

We report on the 29Si nuclear spin decoherence time at room temperature for a pure (99.99999%, 7N) and carrier-less (p-type, doping level of 10^15cm-3) silicon in which 29Si nuclei are naturally abundant (4.7%). Despite the experimental difficulties coming from the extremely long spin-lattice relaxation time T1 (of the order of 10^4 s), we have successfully observed a series of spin-echoes of which the time dependence is characterized by the decoherence time T2. We found that the decoherence process deviates from a single Gaussian or Lorentzian function but is well-reproduced by a bi-exponential function with the shorter T2S = 15\pm5 ms and the longer T2L = 200\pm20 ms.