High Temperature Ferromagnetism in GaAs-based Heterostructures with Mn Delta Doping

TL;DR

This study demonstrates that GaAs-based heterostructures with Mn delta doping can achieve high-temperature ferromagnetism up to 250 K by optimizing growth and annealing processes, with unique Hall effect properties.

Contribution

The paper introduces a novel heterostructure design with controlled Mn doping and annealing to attain high Curie temperatures in GaAs-based semiconductors.

Findings

Achieved ferromagnetic transition temperature up to 250 K.

Reduced Mn interstitials through optimized growth and annealing.

Observed anomalous Hall effect with temperature-dependent sign.

Abstract

We show that suitably-designed magnetic semiconductor heterostructures consisting of Mn delta-doped GaAs and p-type AlGaAs layers, in which the locally high concentration of magnetic moments of Mn atoms are controllably overlapped with the 2-dimensional hole gas wavefunction, realized remarkably high ferromagnetic transition temperatures (TC). Significant reduction of compensative Mn interstitials by varying the growth sequence of the structures followed by low temperature annealing led to high TC up to 250 K. The heterostructure with high TC exhibited peculiar anomalous Hall effect behavior, whose sign depends on temperature.