{'fraction_non_alphanumeric': 0.03064699205448354, 'fraction_numerical': 0.0056753688989784334, 'mean_word_length': 6.0, 'pattern_counts': {'":': 0, '<': 1, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Ultrafast magneto-optics in ferromagnetic III–V semiconductors

We investigate various ultrafast optical processes in ferromagnetic (III,Mn)V semiconductors induced by femtosecond laser pulses. Two-colour time-resolved magneto-optical spectroscopy has been developed, which allows us to observe a rich array of dynamical phenomena. We isolate several distinct temporal regimes in spin dynamics, interpreting the fast (<1 ps) dynamics as spin heating through sp–d exchange interaction between photo-carriers and Mn ions while the ∼100 ps component is interpreted as a manifestation of spin–lattice relaxation. Charge carrier and phonon dynamics were also carefully studied, showing an ultrashort charge lifetime of photo-injected electrons (∼2 ps) and propagating coherent acoustic phonon wavepackets with a strongly probe energy dependent oscillation period, amplitude and damping.