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Full-Text Articles in Engineering

Generalized Form Of Anhysteretic Magnetization Function For Jiles–Atherton Theory Of Hysteresis, A. Raghunathan, Y. Melikhov, J. E. Snyder, David C. Jiles Jan 2009

Generalized Form Of Anhysteretic Magnetization Function For Jiles–Atherton Theory Of Hysteresis, A. Raghunathan, Y. Melikhov, J. E. Snyder, David C. Jiles

David C. Jiles

A generalized form of anhysteretic magnetization function to extend Jiles–Atherton theory to different forms of anisotropy has been derived. The general equation for the function has been compared with those of calculations made on the basis of known equations for specific cases: axially anisotropic (one-dimensional), planar anisotropic (two-dimensional), and isotropic (three-dimensional). The Jiles–Atherton model using the proposed functional form of generalized anhysteretic magnetization function for anisotropy dependence has been validated and the necessary equations derived. It has been shown in this work that this functional form of anhysteretic magnetization with necessary boundary conditions can be reduced to the familiar specific …


Field Induced Structural Phase Transition At Temperatures Above The Curie Point In Gd5(Sixge1−X)4, Ravi L. Hadimani, Y. Melikhov, J. E. Snyder, David C. Jiles Jan 2009

Field Induced Structural Phase Transition At Temperatures Above The Curie Point In Gd5(Sixge1−X)4, Ravi L. Hadimani, Y. Melikhov, J. E. Snyder, David C. Jiles

David C. Jiles

Gd5(SixGe1−x)4 exhibits a field induced first order phase transition from a monoclinic paramagnetic to an orthorhombic ferromagnetic at temperatures above its Curie temperature for 0.41≤x≤0.51. The field required to induce the transition increases with temperature. This field induced first order phase transition was observed even above the projected second order phase transitiontemperature of the orthorhombic phase. This may be due to the fact that the applied magnetic field is so high that it causes the broadening to a wider range of higher temperatures of the second order phase transition of the orthorhombic phase, and at such high magnetic fields the …


Temperature Dependence Of Magnetic Anisotropy Of Germanium/Cobalt Cosubstituted Cobalt Ferrite, N. Ranvah, Y. Melikhov, Ikenna C. Nlebedim, David C. Jiles, J. E. Snyder, A. J. Moses, P. I. Williams Jan 2009

Temperature Dependence Of Magnetic Anisotropy Of Germanium/Cobalt Cosubstituted Cobalt Ferrite, N. Ranvah, Y. Melikhov, Ikenna C. Nlebedim, David C. Jiles, J. E. Snyder, A. J. Moses, P. I. Williams

David C. Jiles

The variations in magnetization and magnetic anisotropy of Ge4+/Co2+ cosubstituted cobaltferrite with temperature were investigated for a series of compositions Co1+xGexFe2−2xO4 (0≤x≤0.4). The magnetization at 5 T and low temperature were observed to increase for all Ge/Co cosubstituted samples compared to pure CoFe2O4. Hysteresis loops were measured for each sample over the magnetic field range of −5 T to +5 T for temperatures in the range of 10–400 K. The high field regions of these loops were modeled using Law of Approach to saturation, which represents the rotational and forced magnetization processes. The first order cubic magnetocrystalline anisotropy coefficient K1 …