EE Times
(04/11/2008 1:14 PM EDT)

PORTLAND, Ore. — A next-generation nonvolatile memory dubbed "racetrack" is expected to initially replace flash memory and eventually hard-disk drives, according to IBM Corp. fellow Stuart Parkin of its Almaden Research Center (San Jose, Calif.)

Using spintronics–the storage of bits generated by the magnetic spin of electrons rather than their charge–a proof-of-concept shift register was recently demonstrated by IBM. The prototype encodes bits into the magnetic domain walls along the length of a silicon nanowire, or racetrack. IBM uses "massless motion" to move the magnetic domain walls along the nanowire for the storage and retrieval of information.

"We have now demonstrated a current-controlled, domain-wall, shift register which is the fundamental, underlying technology for racetrack memory," said Parkin. "We use current pulses to move a series of domain walls along a nanowire, which is not possible to do with magnetic fields."

IBM’s Stuart Parkin

IBM’s goal, based on spintronic patents filed as early as 2004, is to use the same square micron that currently houses a single SRAM memory bit, or 10 flash bits, and drill down into the third dimension to store spin-polarized bits on a sunken racetrack-shaped magnetic nanowire. Using an area of silicon 1 micron wide and 10 microns high, IBM said its first-generation racetrack would store 10 bits compared to one, thereby replacing flash memory. Eventually, it could store 100 bits in the same area, which is dense enough to replace hard-disk drives.

"Racetrack is essentially the third turn of the crank of this new field of engineering called spintronics," said Parkin. "In current solid-state memory devices you store and control the flow of electrical charge. Here, we store and control the flow of the spin of an electron."

Parkin invented a spin valve sensing device in 1989 based on the giant magnetoresistive effect, which was used to increase disk drive capacity 1,000-fold. "Then we invented the use of the magnetic-tunnel junction (MTJ)–a sandwich of two magnetic layers separated by a dielectric–which we used to build the first magnetic random access memories in 1999.

"The third generation is the racetrack, which could replace all nonvolatile memories, including flash memory and hard-disk drives," Parkin claimed.

IBM estimates that an iPod using racetrack memory could store 100 times more information. Unlike flash, the solid-state devices have no components that can wear out.

Racetrack memory injects magnetized domain walls along the length of a high aspect ratio nanowire–only nanometers wide but up to microns long. Spin-polarized current pulses are then used to move the domain walls along the nanowire to store and retrieve bits.

Last year IBM, demonstrated that it could store a magnetic domain on a nanowire, then move it along the wire’s length. The new shift register composed of many domain walls can be stored and moved together along the length of the wire. To read-out bits, the device senses a change in resistance in the wire.

The next step is building a fast MTJ read-head at the top of each racetrack, enabling it to quickly read-out any of the up to 100 bits stored on a racetrack.

IBM’s current prototype uses a linear racetrack aligned parallel to the surface of a silicon chip. The first racetrack demonstration with MTJ read-heads will use that same approach. Eventually, IBM said it plans to build vertical racetracks by sinking nanowires into silicon. The MTJ read-head would be located at the top of each racetrack.

来自IBM公司的研究人员近日表示，一种新的存储设备将在10年内问世，这种存储设备拥有闪存芯片一样的运行速度和效率，但容量高于普通的圆形磁盘片，而且价格比圆形磁盘片低廉得多。
　　IBM称，当前流行的磁盘各自有其缺点：HDD硬盘发热量高，噪音高，体积庞大，但怕震动和敲击，而且有负荷的运动部件容易出错；SSD硬盘体积小、重量轻，负荷的运动部件不易出问题，读取数据速度快，但其写入数据功能不尽人意，而且寿命问题也制约了其优势的发展。

　　据报道，IBM的研究员斯图尔特•帕金（StuartParkin）及其同事在本月的《科学》杂志上发表了他们的这一最新研究成果。IBM的研究人员表示，未来这款存储产品的开发代号为“Racetrack”，它的容量密度达到了目前硬盘技术的100倍以上，其核心技术将用比人的头发丝细10000倍的纳米线来实现记录和检索数据。

　　据悉，Racetrack硬盘需要及其微弱的电能，而且产生极少的热量，普通的电池充电一次就可以带动其运行数周，而且电池可以维持10年左右的时间。