College Park, Maryland      June 6 - 10 , 2004

TP59: Polarized Neutron Studies of Pd40Ni22.5Fe17.5P20 Spin Glass

D.H. Yu, E.P. Gilbert (Bragg Institute, Australian Nuclear Science and Technology Organisation, Australia), R. Woodward (School of Physics, University of Western Australia, Perth, 6009, Australia), R.A. Robinson (Bragg Institute, Australian Nuclear Science and Technology Organisation, Australia)

Magnetic metallic glasses have enormous technological importance in, for example, magnetic recording, magnetic refrigeration and the construction of electrical transformers and motors. Traditionally these amorphous materials were prepared by melt spinning (106 K s-1) to form ribbons. Bulk magnetic metallic glasses based on the quaternary alloy Pd-Ni-Fe-P exhibit interesting phase behaviour depending on temperature and applied magnetic field. For the alloy of Pd40Ni22.5Fe17.5P20, paramagnetic, superparamagnetic, ferromagnetic and spin glass regions are all evidenced [1]. It is proposed that the complex phase transitions in these kinds of materials may be due to the materials not being truly amorphous. The possible large-scale chemical inhomogeneities within the alloy may lead to clustering of magnetic ions. On cooling, frustration due to competing interactions between clusters may result in the observed spin glass-like behaviour. We will present preliminary studies, employing neutron depolarization and small-angle neutron scattering, on the alloy of Pd40Ni22.5Fe17.5P20 as a function of temperature (RT to 5K) and applied magnetic field (0 to 5T).

1 Shen T. D., Schwarz R. B. and Thompson J. D., J. Appl. Phys. 85, 4110-4119, 1999.

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