Modified Surface Electronic and Magnetic Properties of La_0.6Sr_0.4MnO₃ Thin Films for Spintronics Applications

We present the surface electronic and magnetic properties of half-metal La 0.6 Sr 0.4 MnO 3 (LSMO) thin film modified by a simple cleaning procedure, the so-called SC1 (5 H 2 O, 1 NH 4 OH, 1 H 2 O 2 ), at 85 °C for 10–40 min in ambient atmosphere. In this study, photoemission spectroscopy (XPS/UPS), X-ray absorption spectroscopy (XAS), and X-ray magnetic circular dichroism (XMCD) are used to characterize these properties of the manganites. Thanks to SC1 treatment, the work function of LSMO changes from 4.0–4.1 to 4.8–4.9 eV obtained from UPS measurements, while its surface roughness changes from 0.268 to 0.796 nm in AFM images. Combined O 1s, Mn 2p, Sr 3d, La 4d, and Mn 3s core-level XPS spectroscopy investigations suggest that Mn and Sr contents decrease at the surface and the Mn value becomes 3.7 due to SC1 treament. Mn L-edge XAS spectra of LSMO thin film demonstrate that SC1 treatment results in a removal of Mn 2+ and an increase of the Mn 4+ concentration. O K-edge XAS spectra further prove an enhancement of hybridization between O 2p orbitals and e g ↓ of Mn 3d induced by more Mn 4+ . XMCD results show that SC1 treatment does not induce any drastic changes of magnetic properties of the LSMO thin film surface.