Independent Electronic and Magnetic Doping in (Ga,Mn)As Based Digital Ferromagnetic Heterostructures

TL;DR

This paper demonstrates independent electronic doping control in (Ga,Mn)As ferromagnetic heterostructures using atomic layer epitaxy, enabling tunable magnetic and electronic properties with potential spintronics applications.

Contribution

It introduces a method for independent doping of (Ga,Mn)As using superlattices and ALE, reducing defects and maintaining ferromagnetism without MnAs precipitates.

Findings

Ferromagnetic behavior across doping range

No MnAs precipitates detected

Observation of giant planar Hall effect

Abstract

Ferromagnetic semiconductors promise the extension of metal-based spintronics into a material system that combines widely tunable electronic, optical, and magnetic properties. Here, we take steps towards realizing that promise by achieving independent control of electronic doping in the ferromagnetic semiconductor (Ga,Mn)As. Samples are comprised of superlattices of 0.5 monolayer (ML) MnAs alternating with 20 ML GaAs and are grown by low temperature (230 C) atomic layer epitaxy (ALE). This allows for the reduction of excess As incorporation and hence the number of charge-compensating As-related defects. We grow a series of samples with either Be or Si doping in the GaAs spacers (p- and n-type dopants, respectively), and verify their structural quality by in situ reflection high-energy electron diffraction (RHEED) and ex situ x-ray diffraction. Magnetization measurements reveal ferromagnetic behavior over the entire doping range, and show no sign of MnAs precipitates. Finally, magneto-transport shows the giant planar Hall effect and strong (20%) resistance fluctuations that may be related to domain wall motion.