Magnetic properties of (Eu,Gd)Te semiconductor layers

In (Eu,Gd)Te semiconductor alloys, a well known anti ferromagnetic semiconductor compound EuTe is transformed into an n-type ferromagnetic alloy. This effect is driven by the RKKY interaction via conducting electrons, created due to the substitution of Gd3+ for Eu2+ ions. It is expected that due to the high degree of electron spin polarization, (Eu,Gd)Te can be exploited in new semiconductor spintronic heterostructures as a model injector of spin-polarized carriers. (Eu,Gd)Te monocrystalline layers with Gd content up to 5 at. % were grown by MBE on BaF2 (111) substrates with either PbTe or EuTe buffer layers. Measurements of magnetic susceptibility and magnetization revealed that the ferromagnetic transition with the Curie temperature of T-C = 11-15 K is observed in (Eu,Gd)Te layers with n-type metallic conductivity. The analysis of the magnetization of (Eu,Gd)Te was carried out in a broad range of magnetic fields applied along various crystal directions, both in- and out of the layer plane. It revealed, in particular, that a rapid low-field ferromagnetic response of the (Eu,Gd)Te layer is followed by a paramagnetic-like further increase towards a full saturation.