"What the team found was an unexpected magnetic order among the titanium atoms at an interface between strontium titanate and lanthanum manganite, which are both insulators in bulk," Okamoto said.
With today's nano-fabrication tools, scientists can develop artificial materials with controlled precision - almost atom by atom - of alternating very thin crystalline layers of different materials. The properties of these materials are determined by the structure of interfaces of the different materials and how atoms interact through the interfaces.
Such an interface has traditionally been considered a source of disorder, but in the case of materials such as complex oxides used for this study, the result was something that does not exist naturally in any other material. In order to clarify the electronic properties of such interfaces, the research team made detailed synchrotron X-ray measurements.
"The result was even more surprising as we observed a new type of magnetism in titanium atoms, which are non-magnetic in bulk strontium titanate," Okamoto said.
Furthermore, the researchers were able to manipulate the structure of spin, or magnetism, at atomic scale. The theoretical work by Okamoto provided the key to understand the origin of this novel form of interfacial magnetism and is of particular importance for the development of new spintronic devices such as tunneling magneto-resistance junction, which can be used as a head of a hard-disc drive.
While today's electronic devices are based on the transfer of electrical charge between two materials, a potential alternative, spintronic devices, would also use the magnetic moment, or spin, of electrons in addition to their charge and would therefore be more efficient for sending or storing information as an electric signal.
ORNL is managed by UT-Battelle for the Department of Energy's Office of Science.
