Low temperature measurements of the hard magnetic materials.

Hard magnetic materials can be used at low temperatures down to the spin reorientation temperature, Tsr, (eg. around 135 K for Nd-Fe-B). In order to extend the lower limit of usage it is desired to decrease the value of Tsr. This paper reports the influence of different additions and substitutions (Mo, Mo-Cu, Ce) on the hard magnetic properties and Tsr of Nd-Fe-B based films prepared by vacuum deposition. The influence of embedding mode (by alloying or stratification) of additions (i.e. MoCu) in the Nd-Fe-B thin film volume on hard magnetic properties Tsr was also studied. The Nd-Fe-B films with MoCu additions, embedded by stratification, present an increase of the coercive field up to 23.9 kOe and a decrease of Tsr down to 56 K, while Nd-Fe-B films with Ce substitution present a slight deterioration of the magnetic properties and a decrease of Tsr down to 97 K.