  A d-orbital electron has an anisotropic electron orbital and is a source of
magnetism. The realization of a 2-dimensional electron gas (2DEG) embedded at a
LaAlO3/SrTiO3 interface surprised researchers in materials and physical
sciences because the 2DEG consists of 3d-electrons of Ti with extraordinarily
large carrier mobility, even in the insulating oxide heterostructure. To date,
a wide variety of physical phenomena, such as ferromagnetism and the quantum
Hall effect, have been discovered in this 2DEG systems, demonstrating the
ability of the d-electron 2DEG systems to provide a material platform for the
study of interesting physics. However, because of both ferromagnetism and the
Rashba field, long-range spin transport and the exploitation of spintronics
functions have been believed difficult to implement in the d-electron 2DEG
systems. Here, we report the experimental demonstration of room-temperature
spin transport in the d-electron-based 2DEG at a LaAlO3/SrTiO3 interface, where
the spin relaxation length is ca. exceeding 200 nm. Our finding, which counters
the conventional understandings to d-electron 2DEGs, opens a new field of
d-electron spintronics. Furthermore, this work highlights a novel spin function
in the conductive oxide system.
