Exchange-spring behavior in epitaxial hard/soft magnetic bilayer films

摘要

We present results on the magnetic reversal process in epitaxial Sm-Co (1(bar211u001e1)00)/TM (TM = Fe, Co) bilayer films prepared via magnetron sputtering onto Cr-211u001ebuffered single-crystal MgO substrates. The magnetically hard Sm-Co films have 20-211u001eT uniaxial anisotropy and coercivities >3 T at room temperature. The 211u001emagnetization of the soft layer is pinned at the interface to the hard-magnet 211u001elayer and switches reversibly as expected for an exchange-spring magnet. With 211u001eincreasing soft layer thickness, the coercive field of the hard layer becomes 211u001esignificantly less than that of a single layer. We also present numerical 211u001esolutions of a one-dimensional model that provide the spin configuration for each 211u001eatomic layer. Comparison of the experimental results with the model simulations 211u001eindicates that the exchange-spring behavior of our bilayer films can be 211u001eunderstood from the intrinsic parameters of the hard and soft layers.