# 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.

## Key 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.

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Source: https://tomesphere.com/paper/0911.0210