Titanium dxy ferromagnetism at the LaAlO3/SrTiO3 interface.

A number of recent transport and magnetization studies have shown signs of ferromagnetism in the LaAlO₃/SrTiO₃ heterostructure, an unexpected property with no bulk analogue in the constituent materials. However, no experiment thus far has provided direct information on the host of the magnetism. Here we report spectroscopic investigations of the magnetism using element-specific techniques, including X-ray magnetic circular dichroism and X-ray absorption spectroscopy, along with corresponding model calculations. We find direct evidence for in-plane ferromagnetic order at the interface, with Ti³⁺ character in the d_xy orbital of the anisotropic t_2g band. These findings establish a striking example of emergent phenomena at oxide interfaces. [ABSTRACT FROM AUTHOR]