Electrical spin injection from an n-type ferromagnetic semiconductor into a III-V device heterostructure

Area of Science:

• Semiconductor Spintronics
• Materials Science
• Quantum Electronics

Background:

• Ferromagnetic semiconductors (FMSs) offer potential for novel electronic devices.
• Developing n-type FMSs compatible with existing substrates is crucial for integration.
• Spin-polarized electrons are key for advanced semiconductor functionality.

Purpose of the Study:

• To demonstrate electrical spin injection from an n-type FMS into a semiconductor heterostructure.
• To provide a method for directly measuring injected spin polarization.
• To validate theoretical predictions of FMS electronic structure.

Main Methods:

• Epitaxial growth of CdCr(2)Se(4) on an AlGaAs/GaAs substrate.
• Electrical spin injection into a light-emitting diode (LED) structure.
• Analysis of electroluminescence polarization using quantum selection rules.

Main Results:

• Successful electrical injection of spin-polarized electrons from CdCr(2)Se(4) into an LED.
• Direct measurement of injected spin polarization sign and magnitude.
• Confirmation of minority spin injection, aligning with density-functional-theory calculations.
• Demonstration of a reliable method to verify FMS properties and rule out artifacts.

Conclusions:

• Electrical spin injection from n-type FMS is feasible.
• Electroluminescence polarization analysis is a robust tool for characterizing spin polarization.
• This work validates the spin-polarized nature of CdCr(2)Se(4) and its potential for spintronic applications.