Influence of palladium on the unidirectional anisotropy field in NiMn disordered systems

Hadjoudj S., SENOUSSI S., MOSBAH M., Oner Y.

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, vol.175, no.3, pp.328-332, 1997 (SCI-Expanded) identifier identifier


We have carried out AC susceptibility, hysteresis cycle and torque measurements on (Ni76-xPdx)Mn-24, with 0 less than or equal to x less than or equal to 5, bulk alloys in the temperature and field ranges of 4.2-260 K and 0-20 kG, respectively, The AC susceptibility curves, chi'(T), present a maximum at the same freezing temperature, T-g, as the isoelectronic alloy Ni76Mn24. These alloys exhibit also the same Curie temperature, T-c, and the same saturated magnetization, M-s. However, both the unidirectional anisotropy field, H-a, and the coercivity field: H-c, increase considerably with the palladium content. For instance, H-a is 1.5 times larger for (Ni74Pd2)Mn-24 than for Ni76Mn24. The torque measurements give approximately the same H-a at 42 K as the hysteresis cycle. We conclude that Pd impurities enhance unidirectional anisotropy but have practically no effect on T-c, T-g and M-s. This is ascribed to the greater spin-orbit coupling of palladium.