While modern computer technology is based on the transport of electric charge in semiconductors, a promising alternative that may take electronics beyond today's miniaturization limits is the use of an electron’s spin, instead of its charge, to transmit information. Spintronics has become a hot topic as leveraging both the spin and charge of electrons may lead to increased information density and device functionality.
Together with colleagues at the Kyoto University in Japan, scientists at the Walther-Meißner-Institute (WMI) and the Technical University of Munich (TUM) in Garching (Germany) have now demonstrated the transport of spin information at room temperature in a remarkable material system.
In a paper titled "Strong evidence for d-electron spin transport at room temperature at a LaAlO3/SrTiO3 interface" published in Nature, the researchers report the production, transport and detection of electronic spins in the boundary layer between the materials lanthanum-aluminate (LaAlO2) and strontium-titanate (SrTiO3). What makes this material system unique is that an extremely thin, electrically conducting layer forms at the interface between the two non-conducting materials: a so-called two-dimensional electron gas.
The German-Japanese team has now shown that this two-dimensional electron gas transports not only charge, but also spin.
“To achieve this we first had to surmount several technical hurdles,” says Dr Hans Hübl, scientist at the Chair for Technical Physics at TUM and Deputy Director of the Walther-Meißner-Institute. “The two key questions were: How can spin be transferred to the two-dimensional electron gas and how can the transport be proven?”
The scientists solved the problem of spin transfer using a magnetic contact. Microwave radiation forces its electrons into a precession movement, analogous to the wobbling motion of a top. Just as in a top, this motion does not last forever, but rather, weakens in time – in this case by imparting its spin onto the two-dimensional electron gas.