Contribution of carriers to optical conductivity spectra of lanthanum manganites

Nanoscale phase separation in La0.7Ca0.3MnO3films: evidence for texture-driven optical anisotropy

“…The very large free carrier absorption of thick (300 nm) film at T = 80 K makes transmission experiments difficult, so in the FM region the measurements were performed only around T C (figure 1(C)). We observed quite similar behaviour also for self-doped La 0.83 MnO 3 [13] and La 0.7 Sr 0.3 MnO 3 films [14]. Comparative analysis of these spectra and those of other doped manganites (La 1−x (Sr, Ca) x MnO 3 [15,16], Nd 1−x Sr x MnO 3 [17], etc) allows us to conclude that here we are dealing with seemingly universal physical behaviour, common to a wide family of doped manganites.…”

A time-resolved optical study of the paramagnetic dielectric-ferromagnetic metal transition in La0.7Ca0.3MnO3

“…The temperature dependence of the optical conductivity was described using the double exchange model including the dynamic Jahn-Teller effect; it was attributed to changes in the Jahn-Teller polaron, which had a small radius at high temperatures and a large radius at low temperatures [14]. The appearance of the quasi-Drude response in the temperature range in which the resistance is fairly large was, however, explained in [15] by phase separation (according to this model, charge carriers experienced segregation in high-conductivity regions, which had the form offerromagnetic drops in a dielectric matrix). Inelastic neutron scattering measurements gave experimental evidence for phase stratification in manganites; in these experiments, two spin excitation branches with quadratic and linear dispersion laws were recorded [16][17][18].…”

“…It is known that, in the dielectric phase, the optical conductivity spectra have a peak at =:: 1.0 eV, which increases in intensity and shifts to the lower frequencies as the temperature decreases. This peak is also recorded in the ferromagnetic phase and transforms into a Drude response at heliunl temperatures [14,15]. The temperature dependence of the optical conductivity was described using the double exchange model including the dynamic Jahn-Teller effect; it was attributed to changes in the Jahn-Teller polaron, which had a small radius at high temperatures and a large radius at low temperatures [14].…”

Optical indication of metallic clusters in the layered manganites La 2 − 2 x Sr 1 + 2 x Mn 2 O 7 above T CLoshkareva1, Mostovshchikova2, Solin3 et al. 2006Europhys. Lett.3000View full textAdd to dashboardCite

“…It points to the increase of the Drude-like contribution with cooling. In manganites, carriers are moving in narrow band, therefore, the relaxation time is small (∼ 3 • 10 −16 s [9]). This is the reason of the weak dependence of Drude-like contribution in D on the wavelength.…”