Half Metallic Response of Manganite Films at Room Temperature from Spin-Polarized Scanning Tunneling Microscopy

Abstract

The ferromagnetic phase in La0.7Sr0.3MnO3 manganite is completely spin polarized (100%) at room temperature. This is demonstrated on high quality epitaxial films by Spin-Polarized Scanning Tunneling Microscopy. The films consist of a highly homogeneous ferromagnetic (FM) phase in which minority paramagnetic (PM) defects are embedded (less than 1% for best films). PM defects exhibit featureless tunneling spectroscopic characteristics and an insulating-like conductance. FM phase exhibit metallic behavior and strongly nonlinear characteristics. Deconvolution of the spectroscopic curves for the FM phase reveals the totally spin-splitted egt2g manganite bands whose shape and width are in an excellent agreement with optical and photoemission spectroscopy data. These results promote the manganites as efficient spin polarized injectors at ambient conditions.