Premium content
Access to this content requires a subscription. You must be a premium user to view this content.
poster
Improvement in magnetic properties of Nd Fe
Sputtering-made Nd-Fe-B films with the thickness of 20 microns on Si substrates are expected to apply magnetic materials to MEMS (Micro Electro Mechanical Systems) as future devices of a miniaturized sensor and actuator 1. On the other hand, we have fabricated isotropic Nd-Fe-B thick-film magnets thicker than 100 microns on Si substrates by a PLD (Pulsed Laser Deposition) method 2. In addition, micro-magnetization of the thick-films could be achieved by taking advantage of a glass buffer layer 3. Investigation on an optimum condition to enhance magnetic properties of Nd-Fe-B/glass two-layered films, however, has not been completed, since there are many parameters of the fabrication process such as Nd contents, annealing conditions and thicknesses ratio of each film.
In the study, annealing time in a pulse-annealing process after the deposition was optimized at 4.0 s through systematic investigation under Nd contents range from 14 to 16 at.%. Moreover, effect of the thickness ratio of a glass film and an isotropic Nd-Fe-B film on magnetic properties was examined. Figure 1 shows coercivity as a function of the ratio. Here, each thickness varied from 15 to 60 microns for Nd-Fe-B films and 12 to 114 microns for glass films, respectively. It was found that the ratio less than 2 enabled us to increase coercivity up to 500 kA/m. The detail mechanism of the phenomenon is under investigation. In addition, J-H loops of Nd-Fe-B/glass two-layered films on Si substrates were compared as seen in Fig. 2. The red loop and dotted loop are corresponding to an obtained film showed in Fig. 1 and a micro-magnetized film reported in the reference 3, respectively. Enhancement of (BH)max could be achieved through the above-mentioned optimization.
References:
1 R Fujiwara et al., Int. J. Autom. Technol. Vol. 7, 148(2013).
2 M. Nakano et al., IEEE Trans. Magn. Vol. 51, 2102604 (2015).
3 D. Han et al., IEEE Magn. Letters, Vol. 11, 8103804 (2020).
Fig.1 Coercivity of samples as a function of thickness ratio
Fig.2 Comparison of J-H loops of two Nd-Fe-B-glass samples