Double-exchange-like interaction in ${\mathrm{Ga}}_{1-x}{\mathrm{Mn}}_x\mathrm{As}$ investigated by infrared absorption spectroscopy

We have investigated the infrared optical absorption α(ω) of ferromagnetic p-type ${\mathrm{Ga}}_{1-x}{\mathrm{Mn}}_x\mathrm{As}.$ The observed α(ω) showed very non-Drude characteristics, indicating that the holes are nearly localized by disorder. Furthermore, a temperature-dependent spectral transfer between interband and intraband transitions is observed, which strongly suggests that the double-exchange-like mechanism is playing an important role in the ferromagnetic ordering process in III-V diluted magnetic semiconductors. The origin of resistance kinks near $T_c$ (often attributed to “critical scattering”) is also discussed.