Spectroscopic evidence for a charge-density-wave condensate in a charge-ordered manganite:: Observation of a collective excitation mode in Pr0.7Ca0.3MnO3 by using THz time-domain spectroscopy -: art. no. 024401

THz time-domain spectroscopy was used to directly probe the low-energy (0.5-5 meV) electrodynamics of the charge-ordered manganite Pr0.7Ca0.3MnO3. We revealed the existence of a finite peak structure around 2-3 meV well below the charge gap similar to300 meV. In analogy to the low-energy optical properties of the well-studied low-dimensional materials, we attributed this observed structure to the collective excitation mode arising from the charge-density-wave condensate. This finding provides the importance role of the quasi-one-dimensional nature of the charge and orbital ordering in Pr0.7Ca0.3MnO3.