Study of the Long-Range Exchange Coupling in NdFe-B/Ti/Fe Multilayered Structure

Abstract

The exchange coupling between two ferromagnetic thin films, one with magnetically hard and the other with soft phases, separated by a thin non-magnetic layer is studied. Nd-Fe-B/ Ti / Fe thin film heterostructures were fabricated using DC magnetron sputtering on Si substrates which were heated in situ at 650°C using a house-built vacuum-compatible heater. The effect of the thickness of the Ti buffer layer and the annealing temperature on the formation of various phases of NdFeB was investigated. The effect of the thickness of the non-magnetic Ti spacer layer on the exchange coupling strength between the hard phase Nd-Fe-B ferromagnetic thin layer and the soft phase transition metal Fe layer was experimentally investigated. Hysteresis loops of multilayer thin films indicate an antiferromagnetic coupling was observed when the thickness of the spacer layer was 2 nm. This is within the range of antiferromagnetic coupling calculation based on RKKY theory predictions.