The 22nd ESICMM Seminar

The understanding of the influence of temperature on the magnetic properties of permanent magnets is of utmost importance for various application ranging from permanent magnets to heat assisted recording. We present micromagnetic simulations of hard magnetic materials as function of temperature for time scales of seconds and years.  Details on the thermally activated reversal process for exchange spring magnets will be given. The opposite limits of exchange spring structures for permanent magnets and magnetic recording will be discussed.  The importance of local demagnetizing fields will be demonstrated for hot-deformed Nd-Fe-B magnets [1].

In the second part of the talk the influence of temperature pulses above the Curie temperature will be investigated of high coercive films for heat assisted magnetic recording. In particular the study elucidate the question how confined bit transitions can be written when the ambient temperature during recording is close to the Curie temperature [2]. The switching behavior of monolayer as well as composite structures with graded Curie temperature under different external conditions is examined by means of this model.

[1] Thielsch, J., Suess, D., Schultz, L., & Gutfleisch, O. (2013). Journal of Applied Physics, 114(22), 223909.

[2] Evans, R. F. L., Chantrell, R. W., Nowak, U., Lyberatos, A., & Richter, H. J. (2012). Applied Physics Letters, 100(10), 102402.