Resistivity and Seebeck coefficients are reported in the range 50 K & T (300 K for zinc ferrite single crystals Fe3 Zn 04 in the composition range 0 x &0.3. Samples with 0(x~0.012 exhibited first-order phase transformations at the Verwey transition; in the range 0.012(x~0.036 second-or higher-order continuous phase changes were observed. No transitions were encountered for x 0.036. The electrical properties of the zinc ferrites are analyzed in terms of hopping charge-carrier transport involving valence fluctuations on cations located on octahedral sites. The electrical properties and Verwey transitions of Fe3 "Zn, 04 and Fe3(l -g}04 match very well with the compositional correspondence x~~36. Various implications of the above findings are discussed.

Shorted waveguide ferromagnetic resonance ͑FMR͒ measurements were made at 9.5 GHz for pulsed laser deposited yttrium iron garnet ͑YIG͒, MnZn ferrite, and NiZn ferrite films with thicknesses of 1.8, 0.5, and 1.5 m, respectively. The FMR field versus the field angle confirmed the operational assumption of a uniform mode response. For the YIG, the linewidth was 10 Oe when the external field and magnetization vectors were perpendicular to the disk ͑perpendicular FMR͒ and increased smoothly to a maximum value of 27 Oe when the field and magnetization were in the film plane ͑parallel FMR͒. For the MnZn, the linewidth was 49 Oe at perpendicular FMR, increased with the angle between the film normal and the external field to a broad maximum of 80 Oe at 35°, and then dropped to 65 Oe at parallel FMR. For the NiZn, the linewidth was 310 Oe at perpendicular FMR, increased with the field angle to a broad maximum of 1530 Oe at 45°, and then dropped to 960 Oe at parallel FMR. The linewidths were larger than predicted for reasonable values of the Landau-Lifshitz damping and showed angle dependences which indicated nonintrinsic contributions to the loss. Two magnon scattering was used to model these linewidth differences. The angle dependences of the excess linewidths show qualitative agreement with the two magnon predictions, with inhomogeneity sizes in the submicron range and volume fractions below 1%.

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Articles you may be interested inTemperature dependence of spin resonance in cobalt substituted NiZnCu ferrites Appl. Phys. Lett. 97, 182502 (2010); 10.1063/1.3507266 Effect of large magnetocrystalline anisotropy on the spin wave linewidth in Zn-Y hexagonal ferrite J. Appl. Phys. 93, 9195 (2003); 10.1063/1.1572971 High power microwave properties of Zn-Y hexagonal ferrite-parallel pumping size effects Angle dependence of the ferromagnetic resonance linewidth in easy-axis and easy-plane single crystal hexagonal ferrite disks J. Appl. Phys. 81, 7458 (1997); 10.1063/1.365288Spin-wave instability measurements in Mn substituted single-crystal Zn 2 Y hexagonal ferrite thin disks at 8.9 GHz (abstract)Resonance saturation ͑RS͒, subsidiary absorption ͑SA͒, and parallel pump ͑PP͒ spin wave instability threshold measurements have been made on single crystal easy plane disks of Mn substituted Zn-Y type hexagonal ferrite materials at 8.93 GHz and room temperature. For each configuration, ''butterfly curves'' of the spin wave instability threshold microwave field amplitude h crit as a function of the static field applied in the disk plane were obtained. The previous theory for these instability processes was also extended to include planar magnetocrystalline anisotropy and a wave vector k dependent spin wave linewidth, ⌬H k . The RS butterfly curve had a characteristic ''V'' shape with a rounded minimum at the ferromagnetic resonance ͑FMR͒ field. The nominal ⌬H k needed to fit the data at the ferromagnetic resonance field was 7 Oe, but the butterfly curve shape indicated a k-dependent ⌬H k . The butterfly curves for the PP configuration were flat at low field and then diverged rapidly at the cutoff field for first order instability processes, H cut . The SA butterfly curves were also flat over the field interval for first order processes, but then decreased as the field was increased above H cut . This decrease is attributed to the onset of second order processes due to the proximity of the FMR and additional magnetostatic mode peaks as one moves to and then above H cut . The flat portions of the PP and SA butterfly curves could be fitted with a single k-independent ⌬H k value of 18 Oe.

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