相关论文: Polaron Transport in the Paramagnetic Phase of Ele…

In doped manganites, the strong electron-phonon coupling due to the Jahn-Teller effect localizes the conduction-band electrons as polarons. This results in polarons are carriers responsible for transport and ferromagnetic ordering rather…

We report measurements of the resistivity in the ferromagnetic state of epitaxial thin films of La_{1-x}Ca_{x}MnO_{3} and the low temperature specific heat of a polycrystalline La_{0.8}Ca_{0.2}MnO_{3}. The resistivity below 100 K can be…

The Hall coefficient of Gd-doped La_{2/3}Ca_{1/3}MnO_3 exhibits Arrhenius behavior over a temperature range from 2T_c to 4T_c, with an activation energy very close to 2/3 that of the electrical conductivity. Although both the doping level…

A new mechanism is proposed to explain the colossal magnetoresistance and related phenomena. Moving electrons accompanied by Jahn-Teller phonon and spin-wave clouds may form composite polarons in ferromagnetic narrow-band manganites. The…

We present a small-but-sizeable magnetic polaron picture where transport at high temperatures is activated while at low temperatures it is band-like. We show that both double exchange and finite bandwidth effects are important to understand…

We explore the possibility that polaronic distortions in the paramagnetic phase of La$_{0.67}$Ca$_{0.33}$MnO$_3$ manganites persist in the ferromagnetic phase by considering the observed electrical resistivity to arise from coexisting…

Thermoelectric power, electrical resistivity and magnetization experiments, performed in the paramagnetic phase of La_{2/3}Ca_{1/3}MnO_3, provide evidence for polaron-dominated conduction in CMR materials. At high temperatures, a large,…

Temperature dependent electrical resistivity and thermopower measurements were carried out on Gd1-xCaxBaCo2O5.53 with x varying between 0 and 0.25. Ca subsitution leads to the incorporation of holes (Co4+) into the system that leads to a…

The exchange interaction of polaronic carriers with localized spins leads to a ferromagnetic/paramagnetic transition in doped charge-transfer insulators with strong electron-phonon coupling. The relative strength of the exchange and…

We report on the optical properties of the hole-doped manganites Nd_{0.7}Sr _{0.3}MnO_{3}, La_{0.7}Ca_{0.3}MnO_{3}, and La_{0.7}Sr_{0.3}MnO_{3}. The low-energy optical conductivity in the paramagnetic-insulating state of these materials is…

Presently, cerium-doped LaMnO$_3$ is vividly discussed as an electron-doped counterpart prototype to the well-established hole-doped mixed-valence manganites. Here, La$_{0.7}$Ce$_{0.3}$MnO$_3$ thin films of different thicknesses, degrees of…

We have studied structural, magnetic and transport properties as a function of temperature and magnetic field in the electron doped manganite YxCa1-xMnO3, for 0<x<0.25. We found that in the paramagnetic regime, the magnetic susceptibility,…

Zhao et al. [Phys. Rev. B 62, R11 949 (2000)] reported studies of the oxygen-isotope effects on the intrinsic resistivity and thermoelectric power in the paramagnetic state of several ferromagnetic manganites. The isotope effects on the…

Measurements of the low-frequency (f<= 100 kHz) permittivity at T<= 160 K and dc resistivity (T<= 430 K) are reported for La(1-x)Ca(x)MnO(3) (0<= x<= 0.15). Static dielectric constants are determined from the low-T limiting behavior of the…

We have measured the electrical resistance of micrometric to nanometric powders of the La$_{5/8-y}$Pr$_y$Ca$_{3/8}$MnO$_3$ (LPCMO with y=0.3) manganite for hydrostatic pressures up to 4 kbar. By applying different final thermal treatments…

Some possible connection between spin and charge degrees of freedom in magneto-resistive manganites is investigated through a thorough experimental study of the magnetic (AC susceptibility and DC magnetization) and transport (resistivity…

We report anisotropic resistivity measurements on a La$_{1.2}$Sr$_{1.8}$Mn$_{2}$O$_{7}$ single crystal over a temperature $T$ range from 2 to 400 K and in magnetic fields $H$ up to 14 T. For $T\geq 218$ K, the temperature dependence of the…

In the colossal magnetoresistance manganites polarons have been proposed as the charge carrier state which localizes across the metal-insulator transition. The character of the polarons is still under debate. We present an assessment of…

We revisit the transport properties of La-Ca manganites in detail, since they have been confirmed in a number of CMR-exhibiting materials. We also discuss new data considered the hallmark of an unusually high electron-phonon coupling…

Transport properties in doped manganites are studied by considering the Simplified double exchange mechanism in the presence of diagonal disorder. It is modelled by a combination the Ising double exchange with Faliccov-Kimball model. In…