Dependence of Curie Temperature on the Thickness of Epitaxial (Ga,Mn)As Film

TL;DR

This study investigates how the Curie temperature of epitaxial (Ga,Mn)As films varies with thickness, revealing a minimum thickness for ferromagnetism and a decrease in Curie temperature as thickness increases, based on magnetotransport measurements.

Contribution

It provides new insights into the dependence of Curie temperature on film thickness in ultrathin (Ga,Mn)As layers, identifying a minimum ferromagnetic thickness and quantifying the Curie temperature variation.

Findings

Curie temperature is 97 K for the 5 nm layer.

Ferromagnetism disappears below 5 nm thickness.

Curie temperature decreases with increasing layer thickness.

Abstract

We present the magnetotransport properties of very thin (5 to 15 nm) single (Ga,Mn)As layers grown by low temperature molecular beam epitaxy. A lower (Ga,Mn)As thickness limit of 5 nm for the ferromagnetic phase and the dependence of the Curie temperature on (Ga,Mn)As thickness are determined from electrical transport measurements. The Curie temperature is determined to be 97 K for the thinnest ferromagnetic sample and is found to decrease for increasing layer thickness. A carrier density of ~7.1$\times10^{20}$ cm$^{-3}$ for the 5 nm thick (Ga,Mn)As layer is determined from Hall measurements. Differences between magnetotransport properties of thick and thin (Ga,Mn)As layers are observed and discussed.