Field-dependent domain structure evolution in artificial ferrimagnets analyzed by spin-polarized tunnel transport in magnetic tunnel junctions - art.no. 104423

A powerful technique for investigating field-dependent micromagnetism in th in magnetic layers is presented. The technique uses the spin-polarized tunn el-transport mechanism in magnetic-tunnel junctions. We used this technique to study the micromagnetic-reversal mechanism in an artificial ferrimagnet ic system, which consists of two ferromagnetic layers strongly antiferromag netically coupled through a nonmagnetic interlayer. We show that the high s ensitivity of the spin-polarized current to the fluctuations of magnetizati on allows to probe the magnetic-domain structure in the magnetic electrodes . As a contrast to standard M-H and giant magnetoresistance measurements, w hich are only able to probe the global magnetic state of this artificial fe rrimagnet, we show here that the tunnel magnetoresistance discriminates the field-dependent evolution of the domain phases in selective magnetic layer s. Furthermore, we demonstrate the capability of a tunnel-magnetoresistance signal to be used as a quantitative probe for investigating residual walls during the reversal process.