Magnetization dynamics in rare earth Gd3+ doped Mn0.5Zn0.5Fe2O4 magnetic fluid: Electron spin resonance study

作者：Parekh Kinnari^*; Upadhyay R V

来源：Journal of Magnetic Resonance, 2012, 225: 46-51.

DOI：10.1016/j.jmr.2012.10.001

• ESR
• Magnetic fluid
• Ferrite
• Surface spin glass

The electron spin resonance (ESR) technique has been applied to study the spin dynamics in broad temperature range for rare earth doped Mn0.5Zn0.5Fe1.9Gd0.1O4 (MZG5) magnetic fluid. Zero field cooled (ZFC) ESR spectra of MZG5 fluid exhibit an isotropic shift in the resonance field below 40 K, while the field cooled (FC) ESR spectra show a deviation from sin(2)theta behavior and an angle dependent hysteresis, this unambiguously points to the dominating unidirectional freezing of surface spins below 40 K. Above 60K, the resonance field exhibits sin(2)theta behavior, indicating the uniaxial anisotropy contribution of core spin. This indicates that surface spin freezing temperature is around 40 K. The presence of surface spin freezing and the coupling between core and surface spins are further supported by cycle dependent FC ESR spectra measured at 20 K, which show the systematic increase in resonance field (H-res) and intensity. The double peak behavior of blocking temperature distribution retrieved from ZFC-FC magnetization measurement is an additional corroboration of the existence of surface spin glass like layer.

• 出版日期2012-12