We have performed Ti 2p core-level photoemission and X-ray absorption spectroscopic (XAS) studies on the insulating barrier SrTiO3 (STO) layer sandwiched by La0.6 Sr0.4 MnO3 (LSMO) layers. The elemental selectivity of the techniques enabled us to extract the electronic structure of the constituent layers in the vicinity of the heterointerfaces. The Ti 2p core-level and XAS spectra clearly showed Ti4 + states and did not exhibit any indication of Ti3 + states. This result indicates that the Ti ions in the TiO2 atomic layers preserve their tetravalent states even in the vicinity of the valence-mismatched interface between LSMO and STO, reflecting the chemical stability of the Ti4 + states.
- Laser MBE
- Magnetic tunneling junction