The spin transfer torque is a phenomenon in which angular momentum of a spin polarized electrical current entering a ferromagnet is transferred to the magnetization. The effect has opened a new research field of electrically driven magnetization dynamics in magnetic nanostructures and plays an important role in the development of a new generation of memory devices and tunable oscillators. Optical excitations of magnetic systems by laser pulses have been a separate research field the aim of which is to explore magnetization dynamics at short timescales and enable ultrafast spintronic devices. We report the experimental observation of the optical spin transfer torque, predicted theoretically several years ago, building the bridge between these two fields of spintronics research. In a pump-and-probe optical experiment we measure coherent spin precession in a (Ga, Mn)As ferromagnetic semiconductor excited by circularly polarized laser pulses. During the pump pulse, the spin angular momentum of photo-carriers generated by the absorbed light is transferred to the collective magnetization of the ferromagnet. We analyse quantitatively the observed magnetization dynamics triggered by the optical spin transfer torque using independently determined micromagnetic parameters and magneto-optical coefficients of the studied (Ga, Mn)As.
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Fernández-Rossier, J., Núñez, A. S., Abolfath, M. & MacDonald, A. H. Optical spin transfer in ferromagnetic semiconductors. Preprint at http://arXiv.org/abs/cond-mat/0304492 (2003).
Núñez, A. S., Fernández-Rossier, J., Abolfath, M. & MacDonald, A. H. Optical control of the magnetization damping in ferromagnetic semiconductors. J. Magn. Magn. Mater. 272–276, 1913–1914 (2004).
Oiwa, A., Takechi, H. & Munekata, H. Photoinduced magnetization rotation and precessional motion of magnetization in ferromagnetic (Ga, Mn)As. J. Supercond. 18, 9–13 (2005).
Wang, D. M. Light-induced magnetic precession in (Ga, Mn)As slabs: Hybrid standing-wave Damon-Eshbach modes. Phys. Rev. B 75, 233308 (2007).
Takechi, H., Oiwa, A., Nomura, K., Kondo, T. & Munekata, H. Light-induced precession of ferromagnetically coupled Mn spins in ferromagnetic (Ga, Mn)As. Phys. Status Solidi C 3, 4267–4270 (2007).
Qi, J. et al. Coherent magnetization precession in GaMnAs induced by ultrafast optical excitation. Appl. Phys. Lett. 91, 112506 (2007).
Qi, J. et al. Ultrafast laser-induced coherent spin dynamics in ferromagnetic Ga1−xMnxAs/GaAs structures. Phys. Rev. B 79, 085304 (2009).
Rozkotová, E. et al. Light-induced magnetization precession in GaMnAs. Appl. Phys. Lett. 92, 122507 (2008).
Rozkotová, E. et al. Coherent control of magnetization precession in ferromagnetic semiconductor (Ga, Mn)As. Appl. Phys. Lett. 93, 232505 (2008).
Hashimoto, Y. & Munekata, H. Coherent manipulation of magnetization precession in ferromagnetic semiconductor (Ga, Mn)As with successive optical pumping. Appl. Phys. Lett. 93, 202506 (2008).
Hashimoto, Y., Kobayashi, S. & Munekata, H. Photoinduced precession of magnetization in ferromagnetic (Ga, Mn)As. Phys. Rev. Lett. 100, 067202 (2008).
Kobayashi, S., Suda, K., Aoyama, J., Nakahara, D. & Munekata, H. Photo-induced precession of magnetization in metal/(Ga, Mn)As systems. IEEE Trans. Magn. 46, 2470–2473 (2010).
Zutic, I., Fabian, J. & Erwin, S. C. Spin injection and detection in silicon. Phys. Rev. Lett. 97, 026602 (2006).
Burch, K. S., Stephens, J., Kawakami, R. K., Awschalom, D. D. & Basov, D. N. Ellipsometric study of the electronic structure of GaMnAs and low-temperature GaAs. Phys. Rev. B 70, 205208 (2004).
Vanhaverbeke, A. & Viret, M. Simple model of current-induced spin torque in domain walls. Phys. Rev. B 75, 024411 (2007).
Kimel, A. V. et al. Observation of giant magnetic linear dichroism in (Ga, Mn)As. Phys. Rev. Lett. 94, 227203 (2005).
Kirilyuk, A., Kimel, A. V. & Rasing, T. Ultrafast optical manipulation of magnetic order. Rev. Mod. Phys. 82, 2731–2784 (2010).
Jungwirth, T. et al. Systematic study of Mn-doping trends in optical properties of (Ga, Mn)As. Phys. Rev. Lett. 105, 227201 (2010).
Rushforth, A. W. et al. Voltage control of magnetocrystalline anisotropy in ferromagnetic–semiconductor/piezoelectric hybrid structures. Phys. Rev. B 78, 085314 (2008).
De Ranieri, E. et al. Lithographically and electrically controlled strain effects on anisotropic magnetoresistance in (Ga, Mn)As. New J. Phys. 10, 065003 (2008).
We acknowledge fruitful discussions with A. V. Kimel, J. Sinova, J. Wunderlich, J. Fernández-Rossier and A. H. MacDonald, and support from the European Union European Research Council (ERC) Advanced Grant No. 268066 and FP7-215368 SemiSpinNet, from the Ministry of Education of the Czech Republic Grants No. LC510 and MSM0021620834, from the Grant Agency of the Czech Republic Grant No. 202/09/H041 and P204/12/0853, from the Charles University in Prague Grant No. SVV-2012-265306 and 443011, and from the Academy of Sciences of the Czech Republic No. AV0Z10100521 and Preamium Academiae.
The authors declare no competing financial interests.
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Němec, P., Rozkotová, E., Tesařová, N. et al. Experimental observation of the optical spin transfer torque. Nature Phys 8, 411–415 (2012). https://doi.org/10.1038/nphys2279
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