Magnetic semiconductor material holds promise for spintronics

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A new compound that can be integrated into silicon chips could be used to make spintronic devices, according to researchers in the US.

A team from North Carolina State University synthesised the compound, called strontium tin oxide (Sr3SnO), as an epitaxial thin film on a silicon chip. Because Sr3SnO is a dilute magnetic semiconductor, it could be used to create transistors that operate at room temperature based on magnetic fields, rather than electrical current. "We're talking about cool transistors for use in spintronics," commented Dr Jay Narayan, a Professor of Materials Science and Engineering at NC Stata. Spintronics refers to technologies used in solid-state devices that take advantage of the inherent spin in electrons and their related magnetic momentum. "There are other materials that are dilute magnetic semiconductors, but researchers have struggled to integrate those materials on a silicon substrate, which is essential for their use in multifunctional, smart devices. We were able to synthesise this material as a single crystal on a silicon chip." The researchers had set out to create a material that would be a topological insulator. In topological insulators the bulk of the material serves as an electrical insulator, but the surface can act as a highly conductive material – and these properties are not easily affected or destroyed by defects in the material. In effect, that means that a topological insulator material can be a conductor and its own insulator at the same time. Two materials are known to be topological insulators – bismuth telluride and bismuth selenide. But theorists predicted that other materials may also have topological insulator properties. Sr3SnO is one of those materials, which is why the researchers synthesised it. Early results look promising, but the researchers warn that they are still testing the Sr3SnO to confirm whether it has all the characteristics of a topological insulator.