Thickness dependence of the stability of the charge-ordered state in Pr$_{0.5}$Ca$_{0.5}$MnO$_{3}$ thin films
Résumé
Thin films of the charge-ordered (CO) compound Pr$_{0.5}$Ca$_{0.5}$MnO$_{3}$ have been deposited onto (100)-oriented SrTiO$_{3}$ substrates using the Pulsed Laser Deposition technique. Magnetization and transport properties are measured when the thickness of the film is varied. While the thinner films do not exhibit any temperature induced insulator-metal transition under an applied magnetic field up to 9T, for thickness larger than 1100\UNICODE{0xc5} a 5T magnetic field is sufficient to melt the CO state. For this latest film, we have measured the temperature-field phase diagram. Compared to the bulk material, it indicates that the robustness of the CO state in thin films is strongly depending on the strains and the thickness. We proposed an explanation based on the distortion of the cell of the film.