Takeshi Emoto

Magnetic Polarization of Conduction Electrons at Au Layers in Fe/Au Multilayers by 119Sn Mössbauer Spectroscopy

119 Sn Mossbauer measurements were performed for Fe/Au multilayers with 119 Sn probes to study magnetic properties of Au layers. 119 Sn Mossbauer probes were embedded in Au layers of Fe/Au multilayers which were made by ultra-high vacuum evaporation. 119 Sn Mossbauer spectra showed large magnetic hyperfine fields, indicating that Au layers were polarized by ferromagnetic Fe layers. Mossbauer spectra were measured with applied field at 5 K. By computer fitting it was found that the hyperfine fields due to the magnetic polarization have both parallel and antiparallel contributions to the applied field direction.

197Au Mössbauer study of Au/M (M Fe, Co, Ni) multilayers

Abstract 197 Au Mossbauer spectra from Au/M (M  Fe, Co, Ni) multilayers consist mainly of two components. One component shows large hyperfine magnetic fields due to hybridization at the interface between Au and ferromagnetic layers. Another component is a nonmagnetic one arising from the middle part of Au layers that have quite a small perturbation from the adjacent ferromagnetic layers.

197Au Mössbauer study of Au/TM (TM = Fe, Co, Ni) multilayers

Abstract197Au Mössbauer spectra from Au/TM (TM = Fe, Co, Ni) multilayers consist mainly of two components. One component shows a large hyperfine magnetic field due to the hybridization at the interface between Au and ferromagnetic layers. The other component is nonmagnetic arising from the middle part of the Au layers. From the fractional area of the magnetic components in each spectrum, the Au atoms in 0.4 nm Au layers are perturbed by the Fe and Ni layers, and Co layers perturb 0.3 nm Au layers at the interface.

Spin penetration in Au layers: 119Sn Mössbauer study of Co/Au multilayers

Abstract To investigate interlayer coupling and spin polarization in multilayers, Co/Au multilayers in which 119 Sn layers are inserted into Au layers have been prepared and 119 Sn Mossbauer spectra measured. Large hyperfine fields are observed, which means that Sn atoms experience magnetic fields and thus spin polarization induced by Co layers exists in Au layers.

Magnetic polarization of Au layers in Co/Au multilayers observed by 119Sn Mössbauer effect

In order to investigate the magnetic properties of nonmagnetic metal layers in multilayers, we prepared Co/Au multilayers in which 119 Sn layers are inserted into Au layers, and applied Mossbauer spectroscopy. A fraction with large magnetic hyperfine fields was observed in the Mossbauer spectra, and thus magnetic polarization of conduction electrons in nonmagnetic layers is confirmed.

X-ray circular dichroic Bragg reflections from a GdCo/Ag multilayer

Bragg peaks are observed in difference resonant specular reflectivity signals from a GdCo/Ag multilayer in a flipping magnetic field for circularly polarized X-rays. The element-specific X-ray scattering at the L3 absorption edge of Gd directly evidences layers of magnetically ordered Gd ions stacked at a regular spacing of the multilayer 51 A period. The Bragg peaks show a negative polarity, which is accounted for by the property of the resonant magnetic-charge interference scattering.

Relationship between magnetoresistance change and antiparallel magnetization estimated by neutron diffraction in giant magnetoresistance systems

Abstract Magnetization processes in Fe/Cr, Fe/Au and Co/Cu/NiFe/Cu multilayers are investigated by polarized neutron diffraction. A difference in the magnetization vectors of the alternate magnetic layers (antiparallel magnetization) derived from neutron diffraction intensities is compared with the change in the magnetoresistance in various applied fields. The magnetoresistance change during the magnetization process is considered to be proportional to the square of the antiparallel magnetization.

Mössbauer study of Cu/Co and Au/Co multilayers using 119Sn

Abstract Mossbauer absorption spectroscopy has been applied for 119 Sn microprobes located in Cu (or Au) layers of Co/Cu (or Co/Au) multilayers. By observing the hyperfine field, it has been confirmed that spin polarization exists in the middle of the spacer layer with thickness of 20 A. The hyperfine field is significantly larger in Au than in Cu.

197Au Mössbauer study of Au/TM (TM = Fe, Co, Ni) multilayers and alloys

Abstract 197Au Mossbauer spectra from teh Au/TM (TM = Fe, Co, Ni) multilayers consist mainly of two components. One component shows large hyperfine magnetic field due to the hybridization at interface between Au and TM ferromagnetic layers. The largest magnitudes of the hyperfine magnetic fields at the 197Au nuclei are close to the value at 197Au nucleus in the ferromagnetic TM metals. Another component is a nonmagnetic one arising from the middle part of the Au layers. From the area ratio of magnetic components in each spectra, the Au atoms within 0.4 nm Au layer have been perturbed by the Fe and Ni layers, and Co layers perturb 0.3 nm Au layers at the interface.