Magnetic-field-dependent optical studies of a layered antiferromagnet Pr1/2Sr1/2MnO3

Magnetic-field (H)-dependent optical conductivity spectra sigma(omega) and dielectric constant spectra epsilon(omega) of a layered antiferromagnet (A-type) Pr1/2Sr1/2MnO3 were presented. At 0.0 T in 4.2 K, the sigma(w) showed a small Drude-like peak in the far-infrared region and a broad absorption peak in the mid-infrared region, As H increased, large spectral weights were transferred from high- to low-energy regions with increase of the Drude-like peak. We found that a polaron picture could explain most of the H-dependent spectral changes. By analyzing the H-dependent spectral weight changes and epsilon(omega), we showed that a dimensional crossover from a two-dimensional to a three-dimensional metal could occur in Pr1/2Sr1/2MnO3.