Magnetic configurations of a Co monolayer on Cr substrates

The spin polarization of a single Co monolayer on Cr substrates with low-Miller indices is investigated using the tight-binding linear muffin-tin orbital method. For all Cr substrates we consider epitaxial growth of Co. The Co overlayer is ferromagnetic for the (100) and (111) faces while for the (110) direction the stable solution is a C(2 X 2) that gives a zero net magnetization on the Co monolayer. For (100) Cr substrate the effect of the Co overlayer is to decrease dramatically the Cr polarization in the two monolayers underneath the Co and the Co-Cr coupling at the interface is found ferromagnetic. In the case of the (111) surface the effect of Co on the magnetization of the Cr substrate is less pronounced and the Co-Cr coupling is now antiferromagnetic. For the Co monolayer on the (110) surface we obtain a C(2 x 2) solution that gives a zero net magnetization per layer, while for the Co bilayer on Cr(110) we get a ferromagnetic configuration. In both cases the magnetic moments at the Cr interface atoms are strongly reduced.