Ground state and constrained domain walls in Gd/Fe multilayers

The magnetic ground state of antiferromagnetically coupled Gd/Fe multilayers and the evolution of in-plane domain walls is modelled with micromagnetics. The twisted state is characterised by a rapid decrease of the interface angle with increasing magnetic field. We found that for certain ratios M(Fe):M(Gd), the twisted state is already present at low fields. However, the magnetic ground state is not only determined by the ratio M(Fe):M(Gd) but also by the thicknesses of the layers, that is the total moments of the layer. The dependence of the magnetic ground state is explained by the amount of overlap of the domain walls at the interface. Thicker layers suppress the Fe aligned and the Gd aligned state in favour of the twisted state. Whereas ultrathin layers exclude the twisted state, since wider domain walls can not form in these ultrathin layers

Microwave Spectroscopy of a Single Permalloy Chiral Metamolecule on a Coplanar Waveguide

We investigate the microwave spectroscopies of a micrometer-sized single permalloy (Py) chiral structure on coplanar waveguides (CPWs). Under an external dc magnetic field applied in a direction perpendicular to the microwave propagation, the Py chiral structure loaded on the center of the CPW signal line shows Kittel-mode ferromagnetic resonance. Contrastingly, the structure on the signal-line edge highlights two additional resonances: spin-wave resonance at a higher frequency, and unique resonance at a lower frequency of approximately 7.8 GHz. The resonance signal at 7.8 GHz originates from magnetically induced, geometry-driven resonance, although the resonance frequency does not depend on the external magnetic field. Moreover, the displacement of the Py structures on the signal line results in nonreciprocal microwave transmission, which is traced back to the edge-guide mode

Magnetic Polarization of Au Layers in M/Au Metallic Multilayers (M=Fe, Co, Ni) Investigated by Mossbauer Probe Atoms (SOLID STATE CHEMISTRY-Artificial Lattice Allolys)

Magnetic polarization of nonmagnetic Au layers in ferromagnetic/ nonmagnetic metallic multilayers was probed by 119Sn and 57Fe Mossbauer spectroscopy. The Mossbauer probe atoms located in the Au layer with various depths from the interface show depth-dependent large hyperfine field, indicating magnetic polarization in the Au layer. The depth profiles of the magnetic polarization are discussed in Fe/ Au, Co/ Au and Ni/ Au systems