Ferromagnetic (Eu,Gd)Te/PbTe semiconductor heterostructures

Ferromagnetic n-(Eu,Gd)Te/p-PbTe semiconductor heterostructures were grown by molecular beam epitaxy on BaF2 (1 1 1) monocrystalline substrates. The epitaxial growth of the layers was controlled in situ by reflection high-energy electron diffraction. X-ray diffraction and atomic force microscopy techniques revealed high structural and morphological quality of deposited layers. Gd content up to 5 at.% in (Eu,Gd)Te layers was estimated by energy dispersive X-ray fluorescence analysis. Hall effect measurements in (Eu,Gd)Te layers showed very high electron concentration of n ≈ 1020 cm−3 present due to Gd doping. Magnetic characterization of (Eu,Gd)Te/PbTe heterostructures was done using SQUID magnetometry and revealed ferromagnetic transition in n-(Eu,Gd)Te with the Curie temperature TC = 11-15 K. Both in-plane resistance of (Eu,Gd)Te layer and (normal to the plane) (Eu,Gd)Te-PbTe junction resistance measurements were carried out as a function of temperature and magnetic field showing changes in charge transport processes at temperatures close to the Curie temperature.