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A series of Co1-xZnxFe2O4 particulate nano-ferrites with x=0, 0.2, 0.4, 0.5, 0.6, 0.7, and 0.8, fabricated by the co-precipitation method, have been investigated. The lattice parameter is found to increase and particle size decreases with increasing x. Mössbauer spectroscopy at room temperature exhibits ferromagnetic hyperfine splitting sextet peaks with a doublet peak overlapping at its center as Zn contents x<0.6, and only a single doublet as x⩾0.7. The fitting results of Mössbauer spectra reveal the occupation rule of nonmagnetic Zn2+ ions and superparamagnetic behavior. At room temperature, the superparamagnetic excitation plays an important role in the magnetic properties. The fitted hyperfine magnetic field of the octahedral and tetrahedral sublattices decreases with increasing Zn content. The saturation magnetization and coercivity monotonously reduce to a small value. However, at low temperature of 5K, the saturation magnetization (Ms) fully reflects the occupation of Zn ions. Zn substitutions that occupied first the tetrahedral sites cause the increase of magnetization when Zn content is below 0.4, while when Zn content is above 0.4, Zn substitutions occupied both the tetrahedral sites and the octahedral site, which leads to the decrease of magnetization. [ABSTRACT FROM AUTHOR]

The magnetic properties and magnetization damping in a series of Ta(5nm)/Fe20Ni 80Nd0.075(3nm)/Cu(tCunm)/Fe50Co50Gd0.07(3nm)/Cu(2nm) multilayers with varying nonmagnetic Cu layer thickness are investigated by vibrating sample magnetometer and ferromagnetic resonance (FMR). Two-step hysteresis loops are observed, indicative of individual switching of the two magnetic layers. The saturation magnetization of the multilayers possesses a very close magnitude to the sum of those for the Fe20Ni80Nd0.075 and Fe50Co50Gd0.07 single layer films, and the difference between each other is within 3% only. Element-specific hysteresis loops of each magnetic elements involved the multilayers are further probed by x-ray magnetic circular dichroism, which reveals that Fe, Ni, and Co are ferromagnetically coupled with Nd and anti-ferromagnetically with Gd. The FMR spectra for the multilayers exhibit two-resonance peaks originated from the two magnetic layers. Compared with the NiFe-Nd and FeCo-Gd single magnetic films, the linewidth of NiFe-Nd layer in the multilayers shows a large enhancement, while that of the FeCo-Gd layer decreases. Theoretical fitting of the FMR data indicates that the contribution of two-magnon scattering has played an important role in the observed linewidth of single FeCo-Gd films, which, in turn, causes the larger FMR linewidth than that in the multilayers. The intrinsic Gilbert damping constant of both FeNi-Nd and FeCo-Gd layers is found to increase with increasing thickness of nonmagnetic Cu layer from 0.8nm to 2nm. [ABSTRACT FROM AUTHOR]

The magnetic properties of Nd/Ni80Fe20 (Py) bilayer films with different layer thicknesses were investigated. Hysteresis loops were measured at different temperatures, an exchange bias effect is found at low temperature due to the Nd/Py interface. By fitting the temperature dependence of the saturation magnetization, the Néel point of Nd layer is obtained. Ferromagnetic resonance (FMR) experiments were carried out at room temperature as a function of Nd layer thickness. The damping parameter obtained by theoretical fitting of the FMR linewidth shows an increasing trend with increasing Nd layer thickness, which is taken as an indication of the spin pumping effect. [ABSTRACT FROM AUTHOR]

A series of zinc ferrite chains have been synthesized successfully by using the self-assembly method in different synthesizing magnetic fields. The particle chains are arranged in order on the Si substrate under the assistant magnetic field. The zinc ferrite chains show various length-to-radius aspect ratio, saturation magnetization Ms, remanent magnetization Mr, and coercivity Hc in the corresponding synthesizing magnetic fields. Using X-ray magnetic circular dichroism, the Zn substitution mechanism in the ferrite chains has been analyzed and discussed. [ABSTRACT FROM AUTHOR]