Keywords:THz time-domain magneto-spectroscopy, perovskite manganite, colossal magnetoresistance
Doped perovskite manganites (e.g., La1-xSrxMnO3 or LSMO) have attracted considerable interest over the last few decades due to their complex phase diagrams and the discovery of the colossal magnetoresistance (CMR) effect. To date, the origin of the CMR effect and some unusual states, for instance, the ferromagnetic insulator (FI) phase in La0.875Sr0.125MnO3 at low temperatures, are still not well understood. It is challenging to extract the full picture from time-integrated spectroscopy measurements due to the strong interplay among the charge, spin, orbital, and lattice degrees of freedom in the manganites. Ultrafast pump-probe spectroscopy has been suggested as a powerful tool for providing insight into such complex materials by investigating their dynamics after optical excitation. Terahertz (THz) spectroscopy is particularly important to probe low-energy collective excitations such as phonons, magnons, and charge density wave (CDW) condensate. Here, we studied the temperature and magnetic field dependence of THz transmission in LaMnO3 (LMO) and LSMO (x = 0.125) single crystals. The optical conductivity spectra showed basic agreement with expectations based on the known phase diagram but revealed new resonance modes in the THz regime in both crystals. Future work will include optical-pump/THz-probe experiments of both crystals to study light-induced phase transitions.