Dependence of Curie temperature on the thickness of epitaxial (Ga,Mn)As film

We present the magnetotransport properties of very thin (5–15 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 $7.1\times {10}^{20}{\mathrm{cm}}^{-3}$ 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.