Magnetization and structure of Mn-Ni and Mn-Co layered magnetic thin films

The large number of d-like conduction electrons in Mn causes the local moments of Mn to be aligned antiferromagnetically, whereas the smaller number of itinerant d electrons in Fe, Co, and Ni causes the d-conduction electron polarization (dCEP) to align these materials ferromagnetically. With the aim of altering the dCEP in a controlled manner, a series of thin films of total thickness of about 1.2 μ has been prepared by evaporating alternating layers of Ni and Mn or Co and Mn on highly polished oriented sapphire substrates. The layer thicknesses were varied between about 5 and 100 Å. Interference patterns from x-ray measurements indicate that the Ni-Mn films are layered with Ni(111) and predominantly β-Mn (221) layers. The Co-Mn films show predominantly hcp-Co (002) alignment and a Mn alignment which is similar to that of the Ni-Mn films. A wide variety of magnetic behavior is seen in these films, as expected due to the systematic variation of the dCEP across the films.