Electronic Design

MIT Takes New Semiconductor Out For A Spin

Researchers at the Massachusetts Institute of Technology's Francis Bitter Magnet Lab have developed a semiconductor that can improve the use of spintronics. This material could increase computing power while decreasing power consumption. Conventional electronics use an electron's charge state (current on or off) to carry, manipulate, or store information. But spintronics use the electron's spin state (up or down) to carry additional information. Portables like laptops and MP3 players already use spintronics for high-capacity storage.

"We can carry information in two ways at once, and this will further allow us to reduce the size of electronic circuits," says Jagadeesh Moodera, a senior research scientist at the lab and leader of the research team.

The lab's magnetic indium-oxide semiconductor material, which includes a small amount of chromium, sits on top of a conventional silicon semiconductor. It then injects electrons with a given spin orientation into the semiconductor. The spin-polarized electron travels through the semiconductor. A spin detector reads the electrons at the other end of the circuit.

The material can complete this injection at room temperature, and it's compatible with silicon, opening it up to a variety of applications. Its optical transparency also could support applications in solar cells and touchpanel circuitry. Furthermore, spintronic materials like this can lead to more versatile devices, as electron spins can be changed reversibly along circuits using an electron gate.

Spin states are nonvolatile, retaining stored information even when there's no power. Since they wouldn't need current to retain data, information devices based on spintronics would use less power. "In such a system, we can transmit spin information without moving charges," Moodera says. "It's like creating a ripple in a pond—it travels all the way across without adding more energy."

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Massachusetts Institute of Technology
www.mit.edu

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