Depth-selective measurements of induced magnetic polarization in Cu layers of Gd/Cu multilayersby 119Sn Mössbauer spectroscopy

Abstract

We performed 119Sn Mössbauer spectroscopic measurements on Gd/Cu multilayers with119Sn probing atoms. The Cu layers are delta-doped with Sn probes at a certain depth. Hyperfinefields are observed in the Mössbauer spectra at low temperatures below the Curietemperature of the Gd layers. From the temperature-dependent measurements, thehyperfine field is found to be proportional to the spontaneous magnetization ofthe Gd layer. The result indicates that the Gd magnetization induces magneticpolarization in the Cu layers. The hyperfine field per Gd magnetization is found to be∼40 kOe /μB(Gd), regardless of theposition of the 119Sn atoms and the Cu thickness (20–40 Å), suggesting that the magnetic polarization in the Culayer is uniform at any depth from the Gd/Cu interface.