Magnetic nanowire memory

Research and development on immersive and highly realistic video technologies such as 3D video, augmented reality (AR), and virtual reality (VR) has been advancing recently. Such video comprises huge amounts of data, creating a need for recording devices that can read and write data extremely fast, to store the video. NHK Science & Technology Research Laboratories (STRL) has been conducting research on a magnetic nanowire memory that could be used to implement such ultra-fast recording devices in the future.

What is magnetic nanowire memory?

Magnetic nanowires are tiny magnets arranged in a line, with a width of 0.1 μm, approximately 1/1000 the width of a human hair. A magnetic nanowire memory has millions of such wires arranged in parallel, such that digital data can be recorded as the north-south magnetization direction of segments of the wire.

Data is recorded on a magnetic nanowire memory by successively changing the direction of magnetization of small magnetic domains arranged in a line. When recording, the direction of magnetization can be changed in an extremely short time; less than one nanosecond (1 billionth of a second). The data recorded magnetically in the nanowire can also be shifted by passing a current through the length of the wire, so that sequential data can be recorded (Fig. 1). This data shift by electrical current is tens of times faster than operation of a hard disk drive, so by combining recording and data shift, we can expect ultra-fast magnetic recording.

Prototypes and future prospects

We have already prototyped magnetic nanowire memory devices using various magnetic materials and have developed a nanowire material with multilayers of cobalt and terbium that is capable of high-speed data shift. We prototyped a magnetic nanowire memory device combining four wires of this material, data recording metal wires, and electrodes for connecting data recording and shift pulse current sources (Fig. 2). We also confirmed that we can record data on the prototype device and shift the data queue on each of the four magnetic nanowires independently (Fig. 3).

In the future, we will continue development of memory devices with more numbers of magnetic nanowires in parallel, and also apply topological insulators^*1 as a part of magnetic nanowire material that enables even lower power consumption and extremely high speed operation. Our objective is to implement an ideal memory device that can record and read at extremely high speeds with extremely low power consumption.