Since the invention of the first magnetic memory disk in 1954, much effort has been put into enhancing the speed, bit density and reliability of magnetic memory devices. In the case of magnetic random access memory (MRAM) devices, fast coherent magnetization rotation by precession of the entire memory cell is desired1,2,3,4,5,6, because reversal by domain-wall motion is much too slow. In principle, the fundamental limit of the switching speed via precession is given by half of the precession period. However, under-critically damped systems exhibit severe ringing7,8 and simulations show that, as a consequence, undesired back-switching of magnetic elements of an MRAM can easily be initiated by subsequent write pulses, threatening data integrity. We present a method to reverse the magnetization in under-critically damped systems by coherent rotation of the magnetization while avoiding any ringing. This is achieved by applying specifically shaped magnetic field pulses that match the intrinsic properties of the magnetic elements. We demonstrate, by probing all three magnetization components9,10, that reliable precessional reversal in lithographically structured micrometre-sized elliptical permalloy elements is possible at switching times of about 200 ps, which is ten times faster than the natural damping time constant.
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Hiebert, W. K., Stankiewicz, A. & Freeman, M. R. Direct observation of magnetic relaxation in small Permalloy disk by time-resolved scanning Kerr microscopy. Phys. Rev. Lett. 79, 1134–1137 (1997)
Back, C. H. et al. Magnetization reversal in ultrashort magnetic field pulses. Phys. Rev. Lett. 81, 3251–3254 (1998)
Stamps, R. L. & Hillebrands, B. Biased switching of small magnetic particles. Appl. Phys. Lett. 75, 1143–1145 (1999)
Choi, B. C., Belov, M., Hiebert, W. K., Ballentine, G. K. & Freeman, M. R. Ultrafast magnetization reversal dynamics investigated by time domain imaging. Phys. Rev. Lett. 86, 728–731 (2001)
Gerrits, Th. et al. Precession dynamics in NiFe thin films, induced by short magnetic in-plane field pulses generated by a photoconductive switch. J. Magn. Soc. Jpn 25, 192–197 (2001)
Acremann, Y. et al. Ultrafast generation of magnetic fields in a Schottky diode. Nature 414, 51–54 (2001)
Bauer, M., Lopusnik, R., Fassbender, J. & Hillebrands, B. Suppression of magnetic-field pulse-induced magnetization precession by pulse tailoring. Appl. Phys. Lett. 76, 2758–2760 (2000)
Acremann, Y., Back, C. H., Buess, M., Pescia, D. & Pokrovsky, V. Bifurcation in precessional switching. Appl. Phys. Lett. 79, 2228–2230 (2001)
Acremann, Y. et al. Imaging precessional motion of the magnetization vector. Science 290, 492–494 (2000)
Silva, T. J., Pufall, M. R. & Kabos, P. Nonlinear magneto-optic measurement of flux propagation dynamics in thin Permalloy films. J. Appl. Phys. 91, 1066–1073 (2002)
Landau, L. & Lifshitz, E. On the theory of dispersion of magnetic permeability in ferromagnetic bodies. Phys. Z. Union 8, 153–169 (1935)
Crawford, T. M., Kabos, P. & Silva, T. J. Coherent control of precessional dynamics in thin film permalloy. Appl. Phys. Lett. 76, 2113–2115 (2000)
Gerrits, Th. et al. Picosecond control of coherent magnetization dynamics in Permalloy thin films by picosecond magnetic field pulse shaping. J. Magn. Magn. Mater. 240, 283–286 (2002)
Auston, D. H. Impulse response of photoconductors in transmission lines. IEEE J. Quantum Electr. 19, 639–648 (1983)
Frankel, M. Y., Gupta, S., Valdmanis, J. A. & Mourou, G. A. Terahertz attenuation and dispersion characteristics of coplanar transmission lines. IEEE Trans. Microwave Theory Technol. 39, 910–915 (1991)
Keil, U. D. et al. High-speed coplanar transmission lines. IEEE J. Quantum Electr. 28, 2333–2342 (1992)
Keil, U. D., Gerritsen, H. J., Haverkort, J. E. M. & Wolter, H. J. Generation of ultrashort electrical pulses with variable pulse width. Appl. Phys. Lett. 66, 1629–1631 (1994)
Keil, U. D. & Dykaar, D. R. Ultrafast pulse generation in photoconductive switches. IEEE J. Quantum Electr. 32, 1664–1671 (1996)
Holzman, J. F., Vermeulen, F. E. & Elezzabi, A. Y. Recombination-independent photogeneration of ultra-short electrical pulses. Appl. Phys. Lett. 76, 134–136 (2000)
Rasing, Th. Nonlinear magneto-optical probing of magnetic interfaces. Appl. Phys. B 68, 477–484 (1999)
Crawford, T. M., Silva, T. J., Teplin, C. P. & Rogers, C. T. Subnanosecond magnetization dynamics measured by the second-harmonic magneto-optic Kerr effect. Appl. Phys. Lett. 74, 3386–3388 (1999)
Zhu, J. & White, M. Magnetization Reversal and Energy Damping? (Intermag Europe 2002, Amsterdam, The Netherlands, 2002)
Hiebert, W. K., Ballentine, G. E. & Freeman, M. R. Comparison of experimental and numerical micromagnetic dynamics in precessional switching and modal oscillations. Phys. Rev. B 65, R140404-1–R140404-4 (2002)
Kaka, S. & Russek, S. E. Precessional switching of submicrometer spin-valves. Appl. Phys. Lett. 86, 2958–2960 (2002)
Schumacher, H. W. et al. Precessional Magnetization Reversal in Microscopic Spin Valve Cells (Intermag Europe 2002, Amsterdam, The Netherlands, 2002)
The authors wish to thank all members of CTMF1 at Siemens for their collaboration, and for guidance with preparing the devices. This work was part of the research programme of the Stichting voor Fundamenteel Onderzoek der Materie (FOM) and financially supported by the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO), Philips Research and partly supported by the Brite Euram project Tunnel Sense.
The authors declare that they have no competing financial interests.
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Gerrits, T., van den Berg, H., Hohlfeld, J. et al. Ultrafast precessional magnetization reversal by picosecond magnetic field pulse shaping. Nature 418, 509–512 (2002). https://doi.org/10.1038/nature00905
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