Key Concepts

• A radical new design for computer data storage called racetrack memory (RM) moves magnetic bits along nanoscopic “racetracks.”
• RM would be nonvolatile—retaining its data when the power is turned off—but would not have the drawbacks of hard disk drives or present-day nonvolatile chips.
• Chips with horizontal racetracks could outcompete today’s nonvolatile “flash” memory. Building forests of vertical racetracks on a silicon substrate would yield three-dimensional memory chips with data storage densities surpassing those of hard disk drives.
• RM is up against several other new kinds of memory under development.

The world today is very different from that of just a decade ago, thanks to our ability to readily access enormous quantities of information. Tools that we take for granted—social networks, Internet search engines, online maps with point-to-point directions, and online libraries of songs, movies, books and photographs—were unavailable just a few years ago. We owe the arrival of this information age to the rapid development of remarkable technologies in high-speed communications, data processing and—perhaps most important of all but least appreciated—digital data storage.

Each type of data storage has its Achilles’ heel, however, which is why computers use several types for different purposes. Most digital data today, such as the information that makes up the Internet, resides in vast farms of magnetic hard disk drives (HDDs) and in the HDDs of individual computers. Yet these drives, with their rotating disks and moving read/write heads, are unreliable and slow. Loss of data because of so-called head crashes occurs relatively often. Regarding speed, it can take up to 10 milliseconds to read the first bit of some requested data. In computers, 10 milliseconds is an eon—a modern processor can perform 20 million operations in that time.

That is why computers use a second type of storage, solid-state memory, for their computational operations. Solid-state memories read and write data with great speed, enabling swift processing. High-performance versions, such as static and dynamic random-access memory (SRAM and DRAM, respectively), use the electronic state of transistors and capacitors to store data bits. These chips lose their data, however, when the computer powers down—or crashes.

A few computers use nonvolatile chips, which retain data when the power is off, as a solid-state drive in place of an HDD. The now ubiquitous smart cell phones and other handheld devices also use nonvolatile memory, but there is a trade-off between cost and performance. The cheapest nonvolatile memory is a kind called flash memory, which, among other uses, is the basis of the little flash drives that some people have hanging from their key rings. Flash memory, however, is slow and unreliable in comparison with other memory chips. Each time the high-voltage pulse (the “flash” of the name) writes a memory cell, the cell is damaged; it becomes unusable after only perhaps 10,000 writing operations. Nevertheless, because of its low cost, flash memory has become a dominant memory technology, particularly for applications in which the data will not be changed very often.

The computing world is thus crying out for a memory chip with high data density that is also cheap, fast, reliable and nonvolatile. With such a memory, computing devices would become much simpler and smaller, more reliable, faster and less energy-consuming. Research groups around the world are investigating several approaches to meet this demand, including systems based on new electronic components called mem­rist­ors [see DIGITAL ISSUE (link here)] and others making use of spintronics, in which the spin, or magnetism, of electrons plays a key role [see “Spintronics,” by David D. Awschalom, Michael E. Flatté and Nitin Samarth; Scientific American, June 2002].

The answer may lie in a new kind of spintronic chip called racetrack memory (RM), which I proposed in 2002. RM stores bits of data as magnetized regions on nanowires—the “racetracks.” These magnetized regions are as nonvolatile and rewritable as those on an HDD, but the chip needs no moving parts larger than an electron to read and write bits, boosting speed and reliability. The bits themselves zoom along their racetrack, passing a read/write head at a fixed location beside the wire.

Furthermore, the wires may be constructed as vertical columns rising like a forest on a silicon chip. This design breaks free of the limitations inherent in two-dimensional data stores, such as HDDs and all memory chips sold at present, allowing very large data densities. I believe three-dimensional racetrack memory will be the right vehicle to keep information storage technology speeding along the fast lane into a future of data-intensive applications as yet unimagined.

continua en el original en: http://www.scientificamerican.com/article.cfm?id=data-in-the-fast-lanes&sc=WR_20090527