Giant spin accumulation in silicon nonlocal spin-transport devices

TL;DR

This paper demonstrates the creation of a giant spin accumulation in silicon using non-local spin-transport devices with Fe/MgO contacts, achieving significant spin splitting at both low and room temperatures, which advances silicon spintronics.

Contribution

It introduces a method to generate large spin accumulations in silicon by optimizing contact size and material properties, overcoming previous limitations.

Findings

Spin splitting of 13 meV at 10 K and 3.5 meV at room temperature.

Non-local spin signals match numerical spin injection and diffusion models.

Giant spin accumulation results from high tunnel spin polarization and optimized contact size.

Abstract

Although the electrical injection, transport and detection of spins in silicon have been achieved, the induced spin accumulation was much smaller than expected and desired, limiting the potential impact of Si-based spintronic devices. Here, using non-local spin-transport devices with an n-type Si channel and Fe/MgO magnetic tunnel contacts, we demonstrate that it is possible to create a giant spin accumulation in Si, with the spin splitting reaching 13 meV at 10 K and 3.5 meV at room temperature. The non-local spin signals are in good agreement with a numerical evaluation of spin injection and diffusion that explicitly takes the size of the injector contact into account. The giant spin accumulation originates from the large tunnel spin polarization of the Fe/MgO contacts (53 % at 10 K and 18 % at 300 K), and the spin density enhancement achieved by using a spin injector with a size comparable to the spin-diffusion length of the Si. The ability to induce a giant spin accumulation enables the development of Si spintronic devices with a large magnetic response.