Enhancement of the Curie temperature in GaMnAs/InGaMnAs superlattices

TL;DR

This paper demonstrates that embedding InGaMnAs or InGaAs layers within GaMnAs superlattices significantly increases their Curie temperature, with values reaching up to 130 K after annealing, due to compositional and structural optimization.

Contribution

The study introduces a method to enhance Curie temperature in GaMnAs superlattices by embedding InGaMnAs/InGaAs layers and optimizing growth and annealing conditions.

Findings

Curie temperature up to 110 K in superlattices.

Further increase to 130 K after annealing.

High crystalline quality confirmed by X-ray diffraction.

Abstract

We report on an enhancement of the Curie temperature in GaMnAs/InGaMnAs superlattices grown by low-temperature molecular beam epitaxy, which is due to thin InGaMnAs or InGaAs films embedded into the GaMnAs layers. The pronounced increase of the Curie temperature is strongly correlated to the In concentration in the embedded layers. Curie temperatures up to 110 K are observed in such structures compared to 60 K in GaMnAs single layers grown under the same conditions. A further increase in T$_C$ up to 130 K can be achieved using post-growth annealing at temperatures near the growth temperature. Pronounced thickness fringes in the high resolution X-ray diffraction spectra indicate good crystalline quality and sharp interfaces in the structures.