C. Of and A. Idf, the research program of Mairie de Paris and the ERDF European Union grant POIG

K. Yamaguchi, M. Nakajima, and &. T. Suemoto, Coherent Control of Spin Precession Motion with Impulsive Magnetic Fields of Half-Cycle Terahertz Radiation, Physical Review Letters, vol.105, issue.23, p.237201, 2010.
DOI : 10.1103/PhysRevLett.105.237201

J. Nishitani, T. Nagashima, and M. Hangyo, Coherent control of terahertz radiation from antiferromagnetic magnons in NiO excited by optical laser pulses, Physical Review B, vol.85, issue.17, p.174439, 2012.
DOI : 10.1103/PhysRevB.85.174439

T. Kampfrath, Coherent terahertz control of antiferromagnetic spin waves, Nature Photonics, vol.33, issue.1, p.31, 2011.
DOI : 10.1038/nphoton.2010.259

H. Ohno, Making Nonmagnetic Semiconductors Ferromagnetic, Science, vol.281, issue.5379, p.951, 1998.
DOI : 10.1126/science.281.5379.951

J. K. Furdyna, Diluted magnetic semiconductors, Journal of Applied Physics, vol.64, issue.4, p.29, 1988.
DOI : 10.1063/1.341700

F. Perez, J. Cibert, M. Vladimirova, and &. D. Scalbert, exchange coupling, Physical Review B, vol.83, issue.7, p.75311, 2011.
DOI : 10.1103/PhysRevB.83.075311
URL : https://hal.archives-ouvertes.fr/hal-00627896

J. König, H. Lin, and &. H. Macdonald, Theory of Diluted Magnetic Semiconductor Ferromagnetism, Physical Review Letters, vol.84, issue.24, p.5628, 2000.
DOI : 10.1103/PhysRevLett.84.5628

J. B. Héroux, Y. Ino, M. Kuwata-gonokami, Y. Hashimoto, and S. Katsumoto, Terahertz radiation emission from GaMnAs, Applied Physics Letters, vol.88, issue.22, pp.221110-221111, 2006.
DOI : 10.1063/1.2206154

F. J. Teran, Spins Coupled to a Two-Dimensional Electron Gas, Physical Review Letters, vol.91, issue.7, p.77201, 2003.
DOI : 10.1103/PhysRevLett.91.077201

B. Jusserand, Spin Excitations of the Spin-Polarized Electron Gas in Semimagnetic Quantum Wells, Physical Review Letters, vol.91, issue.8, p.86802, 2003.
DOI : 10.1103/PhysRevLett.91.086802
URL : https://hal.archives-ouvertes.fr/hal-00002783

F. Perez, From Spin Flip Excitations to the Spin Susceptibility Enhancement of a Two-Dimensional Electron Gas, Physical Review Letters, vol.99, issue.2, p.26403, 2007.
DOI : 10.1103/PhysRevLett.99.026403
URL : https://hal.archives-ouvertes.fr/hal-01287894

]. C. Aku-leh, F. Perez, B. Jusserand, D. Richards, and &. G. Karczewski, Dynamical corrections to spin-wave excitations in quantum wells due to Coulomb interactions and magnetic ions, Physical Review B, vol.83, issue.3, p.35323, 2011.
DOI : 10.1103/PhysRevB.83.035323
URL : https://hal.archives-ouvertes.fr/hal-01229199

M. Vladimirova, Dynamics of the localized spins interacting with two-dimensional electron gas: Coexistence of mixed and pure modes, Physical Review B, vol.78, issue.8, p.81305, 2008.
DOI : 10.1103/PhysRevB.78.081305
URL : https://hal.archives-ouvertes.fr/hal-00440483

S. Url, ] for details on the sample structure, the THz setup, the intermediate calculations of equations present in the text

J. Gaj, R. Planel, and &. G. Fishman, Relation of magneto-optical properties of free excitons to spin alignment of Mn2+ ions in Cd1???xMnxTe, Solid State Communications, vol.29, issue.5, p.435, 1979.
DOI : 10.1016/0038-1098(79)91211-0

J. M. Bao, L. N. Pfeiffer, K. W. West, and &. R. Merlin, Ultrafast Dynamic Control of Spin and Charge Density Oscillations in a GaAs Quantum Well, Physical Review Letters, vol.92, issue.23, p.236601, 2004.
DOI : 10.1103/PhysRevLett.92.236601

D. Popova, A. Bringer, and S. Blügel, Theory of the inverse Faraday effect in view of ultrafast magnetization experiments, Physical Review B, vol.84, issue.21, p.214421, 2011.
DOI : 10.1103/PhysRevB.84.214421

J. Nishitani, K. Kozuki, T. Nagashima, and &. M. Hangyo, Terahertz radiation from coherent antiferromagnetic magnons excited by femtosecond laser pulses, Applied Physics Letters, vol.96, issue.22, p.221906, 2010.
DOI : 10.1063/1.3436635

B. A. Piot, Fractional quantum Hall effect in CdTe, Physical Review B, vol.82, issue.8, p.81307, 2010.
DOI : 10.1103/PhysRevB.82.081307

C. Weiss, R. Wallenstein, and &. R. Beigang, Magnetic-field-enhanced generation of terahertz radiation in semiconductor surfaces, Applied Physics Letters, vol.77, issue.25, p.4160, 2000.
DOI : 10.1063/1.1334940

P. S. Pershan, J. P. Van-der-ziel, and &. L. Malmstrom, Theoretical Discussion of the Inverse Faraday Effect, Raman Scattering, and Related Phenomena, Physical Review, vol.143, issue.2, p.574, 1966.
DOI : 10.1103/PhysRev.143.574

T. Higuchi, N. Kanda, H. Tamaru, and &. M. Kuwata-gonokami, Selection Rules for Light-Induced Magnetization of a Crystal with Threefold Symmetry: The Case of Antiferromagnetic NiO, Physical Review Letters, vol.106, issue.4, p.47401, 2011.
DOI : 10.1103/PhysRevLett.106.047401

S. G. Carter, Z. Chen, and &. S. Cundiff, quantum wells, Physical Review B, vol.76, issue.20, p.201308, 2007.
DOI : 10.1103/PhysRevB.76.201308

M. C. Hickey and &. J. Moodera, Origin of Intrinsic Gilbert Damping, Physical Review Letters, vol.102, issue.13, p.137601, 2009.
DOI : 10.1103/PhysRevLett.102.137601

¨. O. Soykal and &. M. Flatté, Strong Field Interactions between a Nanomagnet and a Photonic Cavity, Physical Review Letters, vol.104, issue.7, p.77202, 2010.
DOI : 10.1103/PhysRevLett.104.077202

J. Li, Control of magnetic dipole terahertz radiation by cavity-based phase modulation, Optics Express, vol.19, issue.23, p.22550, 2011.
DOI : 10.1364/OE.19.022550

S. Material-for, Terahertz radiation from magnetic excitations in diluted magnetic semiconductors R. Rungsawang, 1 F

F. A. Blum, Inelastic Light Scattering from Semiconductor Plasmas in a Magnetic Field, Physical Review B, vol.1, issue.3, p.1125, 1970.
DOI : 10.1103/PhysRevB.1.1125

J. Gaj, R. Planel, and &. , Relation of magneto-optical properties of free excitons to spin alignment of Mn2+ ions in Cd1???xMnxTe, Solid State Communications, vol.29, issue.5, p.435, 1979.
DOI : 10.1016/0038-1098(79)91211-0

F. Perez, J. Cibert, and M. , exchange coupling, Physical Review B, vol.83, issue.7, p.75311, 2011.
DOI : 10.1103/PhysRevB.83.075311
URL : https://hal.archives-ouvertes.fr/hal-00627896

S. Van-huffel, H. Chen, &. C. Decanniere, and P. , Algorithm for Time-Domain NMR Data Fitting Based on Total Least Squares, Journal of Magnetic Resonance, Series A, vol.110, issue.2, p.228, 1994.
DOI : 10.1006/jmra.1994.1209