Light Increases Magnetic Memory Speeds

Schematic design to potentially reduce energy consumption in magnetic memory devices and improve their speeds. (Source: Purdue U.)

Internet searches, decade-old emails and on-demand video offerings help contribute to elec­tricity consump­tion by America’s server farms and data centers amounting to more than 2 percent of the country’s annual total. Those data centers – which operate millions of drives and hold massive amounts of digital data – use some 70 billion kilowatt hours per year of energy. Now, a method that can poten­tially reduce energy consumption in magnetic memory devices and improve their speeds is advancing at Purdue Uni­versity. The method involves a combi­nation of spintronic and photonic materials, where ultrashort laser pulses are employed to generate intense magnetic fields to mani­pulate the spin orientation of magnetic materials.

“We have brought together these two fields to derive a solution to a decades-old problem,” said Ernesto Marinero, a professor of materials engi­neering and electrical and computer engi­neering in Purdue’s College of Engineering. “We wanted to figure out faster ways of switching the magne­tization in spintronic nanoscale memory devices.” Marinero worked with Vlad Shalaev and Alexandra Boltasseva, photonics experts and professors in Purdue’s College of Engineering, to develop a new magneto-photonics effort to employ light to control magne­tization processes for a variety of appli­cations – resulting in ultra-fast switchable devices.

“We are among the first to success­fully develop a method for all-optical switching of on-chip nano­magnets in high-density memory modules,” Marinero said. This emerging technology involves collective electron waves, or plasmons, triggered when light strikes a nanoscale material such as a metal that can sustain the electron waves. These plasmons generate intense, ultra-short magnetic fields at the interface of judi­ciously chosen optical and magnetic materials.

By changing the properties of the incident light, the direction of the resulting magnetic field is reversed, which enables the mani­pulation of the magnetic orien­tation in the magnetic material, a critical require­ment for magnetic information storage. Numerical simu­lations conducted by Aveek Dutta, a graduate student in engineering, predict large magnetic field enhance­ments driven by induced plasmon exci­tations.

The Purdue team’s method involves using the power of optics through localized surface plasmon resonances, to couple light to nano­magnets and produce faster spintronic devices switching speeds and potential lower energy consump­tion. The light enables switching of the magneti­zation orien­tation, the key principle behind encoding information digitally in magnetic storage devices. “We believe that our method could ulti­mately lead to memory writing speeds that are 1,000 times faster than current ones,” Marinero said. “One of our key areas for success is continuing to develop materials that interact with the magnets in an efficient way.” (Source: Purdue U.)

Link: Materials Engineering (E. Marinero), Purdue University, West Lafayette, USA

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