COERCIVITY AT CRYOGENIC TEMPERATURES IN PR2(CO1-XMNX)14B AND PR2(FE1-XMNX)14B

The crystallographic and magnetic properties of Pr2(Co1-xMnx)B-14 and Pr2 Fe1-xMnx)B-14 were studied by X-ray diffraction and magnetic measurements. A large coercive force of up to 16 kOe and 22 kOe for Pr2(Co1-xMnx)B-14 and Pr2 Fe1-xMnx)B-14 respectively was observed at 1.5 K in as-cast bulk samples of the pseudoternary compounds. The coercivity is intrinsic in nature as it is observed in homogeneous single-phase materials. The intrinsic coercive force (i)H(c) shows a composition dependence. The form of the virgin magnetization curves is characterized by a propagation field Hp indicating that the coercive force is created by domain wall pinning. A relation between the coercive force and the thermal activation energy was elucidated by the temperature dependence of (i)H(c). The origin of the large value of coercive force can be understood in terms of narrow domain walls.Chemistry, PhysicalMetallurgy & Metallurgical EngineeringSCI(E)EI0ARTICLE2195-20016