A Digital Switch and Femto-Tesla Magnetic Field Sensor Based on Fano Resonance in a Spin Field Effect Transistor

TL;DR

This paper proposes a spin field effect transistor utilizing Fano resonances for ultra-sensitive magnetic field detection and low-power digital switching, achieving femto-Tesla sensitivity with minimal voltage swings.

Contribution

It introduces a novel spin transistor design exploiting Fano resonances for digital switching and magnetic sensing, with potential for ultra-low power and high sensitivity applications.

Findings

Fano resonances enable digital switching with microvolt gate voltages.

Array of transistors can detect magnetic fields as small as 1 femto-Tesla/√Hz.

The device operates efficiently at low temperatures with minimal power dissipation.

Abstract

We show that a Spin Field Effect Transistor, realized with a semiconductor quantum wire channel sandwiched between half-metallic ferromagnetic contacts, can have Fano resonances in the transmission spectrum. These resonances appear because the ferromagnets are half-metallic, so that the Fermi level can be placed above the majority but below the minority spin band. In that case, the majority spins will be propagating, but the minority spins will be evanescent. At low temperatures, the Fano resonances can be exploited to implement a digital binary switch that can be turned on or off with a very small gate voltage swing of few tens of microvolts, leading to extremely small dynamic power dissipation during switching. An array of 500,000 x 500,000 such transistors can detect ultrasmall changes in a magnetic field with a sensitivity of 1 femto-Tesla/sqrt{Hz}, if each transistor is biased near a Fano resonance.