Micromagnetic analysis of remanence and coercivity of nanocrystalline Pr-Fe-B
D. Suess, M. Dahlgren, T. Schrefl, R. Grössinger, and J. Fidler
Journal of Applied Physics -- May 1, 2000 -- Volume 87, Issue 9, pp.
Nanocrystalline exchange coupled Pr11.76Fe82.36B5.88
single-phase and Pr9Fe85B6 two-phase magnets
containing 20 vol % α-Fe were produced using mechanical alloying.
Micromagnetic finite element simulations were used to analyze the
temperature dependence of the magnetic properties. In the single-phase
exchange-coupled magnet a significant enhancement of the remanence Jr
= 1.1 T was achieved at room temperature. A further enhancement of the
remanence was observed in two-phase α-Fe containing magnets reaching
a remanence of Jr = 1.23 T. The corresponding values of the
coercive field are µ0Hc= 0.81 T and µ0Hc
= 0.57 T for the single-phase magnet and the two-phase magnet, respectively.
Remanence enhancement becomes more effective with increasing temperature,
compensating the decrease of the saturation polarization. In the two-phase
magnet the remanence increases from Jr = 1.12 to Jr =
1.23 T as the temperature is increased from 200 to 300 K. Micromagnetic
calculations clearly show that the increase of the exchange length with
increasing temperature improves the effective coupling between the Pr2Fe14B
and the α-Fe phase. The decrease of the coercive field with increasing
temperature has to be attributed to the temperature dependence of the anisotropy
field. (C)2000 American Institute of Physics.
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Feb. 13, 2001