Comment on "Control of Spin Precession in a Spin-Injected Field Effect Transistor" [Science, 325, 1515 (2009)]

TL;DR

This paper critiques a previous claim of demonstrating the Datta-Das Spin Field Effect Transistor, arguing that the theoretical equation used is only valid in one dimension and does not support the original conclusion.

Contribution

It clarifies the limitations of the theoretical model used in the original study, challenging the validity of their experimental agreement.

Findings

The theoretical equation is only valid for one-dimensional transistors.

The claimed agreement in the original paper is not meaningful for two-dimensional structures.

The original claim of demonstrating the spin transistor is not substantiated.

Abstract

A recently published report in the journal Science claims that the Datta-Das Spin Field Effect Transistor has been demonstrated because an exact agreement was found between the voltage modulation in a fabricated structure and a theoretical equation that supposedly describes the voltage modulation of the Datta-Das Transistor. Here, I show that the said theoretical equation holds only for a one-dimensional transistor, or perhaps a quasi one-dimensional transistor, and is certainly not applicable to the two-dimensional transistor studied. Hence, the exact agreement is meaningless and does not substantiate the claim.