Epitaxial NdCo5/SmCo5 bilayers

RECo5 magnets are of interest due to their strong magnetocrystalline anisotropies, which in some cases change with temperature. This work presents epitaxial NdCo5/SmCo5 bilayers, in which NdCo5 undergoes a spin reorientation transition from easy axis along the c-axis above 310 K to easy plane below 255 K while SmCo5 keeps the uniaxial anisotropy in the whole temperature range. The films were prepared on Cr buffered MgO(110) substrates resulting in a growth of the RECo5 with a single orientation of the c-axis parallel to the film plane. In a first step, the magnetic behavior of single NdCo5 thin films have been investigated and it was found that they possess intrinsic magnetic properties and especially a spin reorientation transition in good agreement with single crystal data. To analyze the magnetic coupling of the bilayer system, a series with a fixed thickness of the SmCo5 layer and a varying thickness of the NdCo5 have been prepared. Phase formation and texture were controlled with XRD and texture measurements. The magnetic properties in a temperature range between 20 and 400 K have been measured with Vibrating Sample Magnetometry.