By James Devitt
January 3, 2013
A discovery by NYU physicists that has potential to significantly enhance computer memory was cited by Applied Physics Letters as “one of the most notable” articles the journal has published over the past four years.
The work creates a new type of “spin-based memory” that has the potential to replace all conventional memory, such as the semiconductor memory in computers and portable devices.
The article was authored by NYU’s Huanlong Liu, a doctoral student, postdoctoral researchers Daniel Bedau and Dirk Backes, and physics professor Andrew Kent, along with researchers at HGST and Singulus Technologies in Kahl am Main, Germany.
“Spin-based memory” seeks to manipulate magnetism of different materials in response to electric currents and fields. The magnetic coupling occurs through the exchange or flow of electron “spin angular momentum”—the fundamental property of electrons that gives rise to magnetism in materials. When a current flows in a magnetic material, the spins of the electrons move and can transport spin angular momentum from one region to another. This transport of spins can cause the magnetization to rotate, like a breeze on a windy day can cause a wind turbine to rotate.
In the Applied Physics Letters article, the research team, led by NYU physicist Kent, describes how it sought to store information using nanomagnets—a billionth of a meter in size—in order to write information with spin-current pulses.
This approach improves upon what is typically used in computers and portable devices, semiconductor random access memory (RAM), which involves storing information by charging a capacitor. However, this charge leaks away and thus the device needs to be read and refreshed periodically. For example, dynamic RAM (DRAM), currently the fastest type of computer memory, is refreshed 1,000 times per second, consuming a great deal of energy. By contrast, nanomagnets retain their direction of magnetization without the need for a source of energy. In fact, energy is needed only to write or read the information, not to retain it.
The NYU device is called an orthogonal spin-transfer magnetic RAM-OST-MRAM ™
The technology is being commercialized by Spin Transfer Technologies, Inc., a company funded by Allied Minds, a Boston-based seed investment corporation, as well as Invesco.
“The memory device is both significantly faster and requires much less energy than a conventional memory, offering the potential for more energy-efficient computing devices,” explains Kent.