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Electron microscope image of a magnetic nano wire with electric contacts

Precessional magnetization reversal

Working Group 2.52

The fastest possible magnetization reversal process is the so-called ballistic magnetization reversal. In this optimum reversal process the magnetization undergoes exactly a 180° degree precessional turn and precesses directly from the initial to the final reversed equilibrium orientation. A calculated trajectory of such a ballistic magnetization reversal process is shown in Fig.1.

 

The duration of the transverse magnetic field pulse is exactly matched to the half of the precession period
( T Pulse = ½ . T Prec ).
Upon pulse decay M is oriented along the final equilibrium orientation along the easy axis and no subsequent precession (“ringing” of the magnetization) occurs.




Fig. 1 : Ballistic magnetization reversal by a transverse field pulse. The field pulse amplitude is 200 Oe; field pulse duration is 163 ps.

In [ 12 ] the experimental realization of precessional an ballistic magnetization reversal of magnetic memory cells is described.

Literature:

[1] H. W. Schumacher, C. Chappert, P. Crozat, R. C. Sousa, P. P. Freitas, J. Fassbender, B. Hillebrands: Phys. Rev. Lett. 90, 017201 (2003)

[2] H. W. Schumacher, C. Chappert, R. C. Sousa, P. P. Freitas, J. Miltat: Phys. Rev. Lett. 90, 017204 (2003).