Precessional switching of a 3×1 micrometer elliptical element in a crossed-wire geometry

Abstract

Switching dynamics of a thin-film 3×1 micrometer elliptical permalloy element in a crossed-wire geometry was investigated for different pulsed field amplitudes using time resolved scanning Kerr microscopy. We observed coherent switching of magnetization by fast-risetime hard axis magnetic field pulses. The combined action of easy- and hard-axis fields resulted in reliable half-select switching of the sample magnetization. Varying the delay between the pulses one can control the postswitching oscillations of magnetization or eliminate them altogether achieving an ultrafast half-select switching of risetime of just 180 ps. Our results agree quantitatively with Landau–Lifshitz–Gilbert-based micromagnetic simulations.

Frequency analysis of the magnetization dynamics in thin ellipsoidal magnetic elements

“…This will stop the magnetization exactly in the reversed direction without any further oscillations, so-called ringing, that would otherwise slow down the overall reversal process. [6][7][8][9][10] Severals groups have studied the magnetization dynamics in thin patterned elements, 11,12 including the effects of defects and the resulting additional damping, 13 the localized precession modes that may exist in such elements, [14][15][16][17] and the approach for reducing the crosstalk between neighboring bits. 18,19 A particular problem is how to design an optimal field pulse to switch an element within half a precession period and then stopping the magnetization without any ringing.…”

Effects of spin-polarized current on pulse field-induced precessional magnetization reversal

“…The fastest reversal is obtained when the magnetization precession is stopped after a half period of a full precession, and the switching time is only a few hundred picoseconds. [6][7][8][9][10][11][12][13][14] T. Gerrits et al 7 demonstrated that a reliable precessional reversal in micrometre-sized elliptical permalloy element is possible at switching time of about 200 ps. H. Schumacher et al 9 also realized a quasi-ballistic reversal with switching time was as short as 165 ps in a spin valve.…”

“…22,23 In addition, after the a Author to whom correspondence should be addressed; Electronic mail: guogh@mail.csu.edu.cn precessional reversal, a residual magnetization oscillation or ringing around the new equilibrium state persists for several nanoseconds. [12][13][14]24 This increases the time needed to execute consecutive switching events. Effective suppression of the magnetization ringing is necessary and still remains to be a problem for the application of precessional reversal in ultrafast magnetic devices.…”

Effective bit addressing times for precessional switching of magnetic memory cells

“…9,10 Further studies addressed the question of bit selection in a MRAM by using combined pulses from two independent pulse lines to switch the magnetization of a cell. 11,12 Both for a single transverse pulse 7,9 and for combined pulses 12 magnetization switching on optimal so-called quasiballistic 1,2 trajectories was possible which is crucial for fast memory operation. Here, we use ultrafast magnetotransport to study the time evolution of switching and nonswitching in bit-selected microscopic magnetic tunnel junctions ͑MTJs͒.…”