Polycrystalline and laminated La0.7Sr0.3MnO3 films made by pulsed laser deposition

Abstract

Highly smooth and particulate free relatively thick polycrystalline La0.7Sr0.3MnO3 films out to 6 μm thick have been grown by shadowed pulse laser deposition at 30 Hz (248 nm, 500 mJ). Such films exhibited a low field and high field magnetoresistance as previously reported by a number of groups. Multilayer films made with alternating 8-nm-thick barium ferrite and 16-nm-thick La0.7Sr0.3MnO3 laminations exhibited the same high field response, but did not exhibit the low field magnetoresistance component. This is consistent with the low field component arising from intergrain scattering. Patterned films have been simultaneously deposited onto R-plane, C-plane, and polycrystalline alumina substrates. The films were postannealed at 750 K in 200 Torr O2 for 45 min. The low field magnetoresistance was most pronounced for the single layer films made onto C-plane sapphire and then polycrystalline alumina substrates. The films exhibited a broad maximum in resistivity versus temperature at 162, 210, and 218 K for films grown onto R-plane sapphire, C-plane sapphire, and alumina substrates, respectively. Restricted grain size films made with La0.7Sr0.3MnO3 and barium ferrite laminations exhibited a single linear magnetoresistance response of −0.43%/kOe for in plane applied fields of ±10 kOe.