X. J. Chen

Strain effect on electronic transport and ferromagnetic transition temperature in La 0.9 Sr 0.1 MnO 3 thin films

We report on a systematic study of strain effects on the transport properties and the ferromagnetic transition temperature T c of high-quality La 0 . 9 Sr 0 . 1 MnO 3 thin films epitaxially grown on (100) SrTiO 3 substrates. Both the magnetization and the resistivity are critically dependent on the film thickness. T c is enhanced with decreasing the film thickness due to the compressive stain produced by lattice mismatch. The resistivity above 165 K of the films with various thicknesses is consistent with small polaronic hopping conductivity. The polaronic formation energy Ep is reduced with the decrease of film thickness. We found that the strain dependence of T c mainly results from the strain-induced electron-phonon coupling. The strain effect on E P is in good agreement with the theoretical predictions.

Low-temperature electrical transport in bilayer manganite La 1.2 Sr 1.8 Mn 2 O 7

The temperature T and magnetic-field H dependences of anisotropic in-plane

Small-polaron hopping conductivity in bilayer manganite La

{\ensuremath{\rho}}_{\mathrm{ab}}

_{1.2}

and out-of-plane

Sr

{\ensuremath{\rho}}_{c}

_{1.8}

resistivities are investigated in single crystals of the bilayer manganite

Mn

{\mathrm{La}}_{1.2}{\mathrm{Sr}}_{1.8}{\mathrm{Mn}}_{2}{\mathrm{O}}_{7}.

_{2}

Below the Curie transition temperature

O

{T}_{c}

_{7}

=125 K,