Breakthrough: First 3D Metamaterial Revolutionizes Data Storage

European researchers have made a groundbreaking discovery by developing a 3D metamaterial capable of storing sequences of data bits for the very first time. This remarkable achievement is the result of collaborative efforts from a team of experts hailing from the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), TU Chemnitz, TU Dresden, and Forschungszentrum Jülich.

The researchers have successfully demonstrated that not only individual bits but entire sequences of data bits can be stored within cylindrical domains measuring approximately 100nm. These cylindrical areas hold immense potential for the development of innovative data storage devices and sensors, including magnetic variations of neural networks.

The metamaterial comprises blocks of cobalt and platinum arranged in alternating layers, interspersed with ruthenium layers, all deposited on silicon wafers. This synthetic antiferromagnet boasts a unique vertical magnetization structure where adjacent layer blocks exhibit opposite directions of magnetization, resulting in an overall neutral magnetization.

Prof. Olav Hellwig from HZDR’s Institute of Ion Beam Physics and Materials Research explains, “A cylindrical domain, a bubble domain, is a cylindrical area in a thin magnetic layer where spins point in a specific direction, creating a distinct magnetization. Imagine a small, cylinder-shaped magnetic bubble floating amidst an environment of opposite magnetization.”

Domain walls emerge at the edges of these cylindrical domains, forming fringe areas where the magnetization direction changes. Precise control over the spin structure within these domain walls is crucial in magnetic storage technology, as the clockwise or counterclockwise direction can directly encode bits. Researchers are also exploring ways to enhance mass storage capabilities.

“Our current hard disks, with track widths of 30 to 40 nanometers and bit lengths of 15 to 20 nanometers, can store around one terabyte on a postage stamp-sized surface. To overcome data-density limitations, we are delving into three-dimensional storage,” says Hellwig.

Magnetic multilayer structures offer a promising avenue for manipulating the internal spin structure of domain walls by adjusting the magnetic energies through a combination of different materials and layer thicknesses.

The concept of ‘racetrack’ memory plays a pivotal role in this research. Hellwig elaborates, “Bits are arranged along a racetrack, akin to a string of pearls. By precisely controlling layer thicknesses and magnetic properties, we can tailor the behavior of the synthetic antiferromagnet to store entire bit sequences through depth-dependent magnetization direction of domain walls.” This advancement paves the way for efficient transportation of multi-bit cylinder domains along magnetic data highways.

Besides data storage applications, the metamaterial holds promise for applications in magnetoelectronics, such as magnetoresistive sensors and spintronic components. Furthermore, these intricate magnetic nano-objects could revolutionize magnetic implementations in neural networks, potentially mimicking the data processing capabilities of the human brain.

For more information, visit www.hzdr.de.