The structural and magnetic phase transition in FeRh thin films are investigated. The ͑001͒ oriented single crystal FeRh thin films fabricated onto MgO ͑100͒ substrate possess lattice parameter a smaller than c, because of the compressive stress along the a axis from MgO substrate. With increasing annealing temperature, paramagnetic FeRh thin films transform into ferromagnetic and then antiferromagnetic-ferromagnetic ͑AF-FM͒ stages. The transition temperature of AF-FM increases with annealing temperature, while the thermal hysteresis width decreases. The M-H loops of the film annealed at 700°C show an opening at high magnetic fields during the transition state. Note that the opening in M-H loops disappears when AF phase has transformed into FM phase. The origin of the opening is not known but possibly due to the combination of hysteresis loops of FM and AF phases, where FM phase is soft magnetic and the AF phase FeRh shows a hysteresis behavior with coercivity due to the reduction of magnetic anisotropy at high temperatures. The abrupt change of coercivity along the perpendicular direction during the AF-FM transition suggests that a stress-induced magnetic anisotropy exists in FeRh thin films due to the volume expansion in the phase transition process.

An abnormal behavior of increasing magnetic anisotropy with temperature in magnetic thin films fabricated by a gradient-composition sputtering technique is observed and consistently confirmed by two independent measurements of static magnetic hysteresis loops and dynamic magnetic permeability spectra. This peculiar behavior is suggested to be due to the physical origin of stress-induced magnetic anisotropy.

Through a systematic investigation of the field-dependent dynamic magnetization of a series of NiFe films with and without stripe domains in conjunction with the static magnetization process, we demonstrate that the experimental rotatable anisotropy field is not a fixed value but strongly varied with the external in-plane magnetic field, being qualitatively associated with the emergence of stripe domains. Moreover, the frequency linewidth spectra of the films with stripe domains show an abnormal behavior with three distinct regimes which are strongly correlated with both the static magnetization process and the competition between external magnetic field and dynamic anisotropy field. The results are discussed in terms of the effect of inhomogeneous magnetization associated with the formation of stripe domains and the field-dependent dynamic anisotropy that cause the broadening of frequency linewidth.

Hybrid multilayers of [FeNi–FeMn]N/[MnIr–FeCo]N deposited onto flexible substrates oriented for wideband noise filters were fabricated using rf sputtering deposition. By combining the two types of multilayers with various thicknesses, where FeNi–FeMn is designed for the low frequency range and MnIr–FeCo for the high frequency range, one can realize a hybrid thin film for wideband noise filters. Its broad range from 1.5 to 7 GHz (the absorption width where the reflection loss is less than −10 dB) makes this hybrid thin film promising for future applications.

Through a systematic investigation, we demonstrate that FeCoZr thin films deposited by gradient composition sputtering technique possess a unique magnetic thermal behavior, namely, the increase in magnetic anisotropy with temperature. Moreover, this gradient composition sputtering technique also offers a viable method to tailor the high-frequency magnetic properties as well as their thermal stability by changing deposition angle and deposition power. The unusual temperature dependence of magnetic anisotropy in such thin films can be interpreted in terms of stress-induced magnetic anisotropy arising from the composition gradient in the films.