A depiction of the global order of magnetic charge ice. Orange-red areas represent the positive charges; blue areas represent negative charges. Credit: Yong-Lei Wang and Zhili Xiao
A team has created a new material, called “rewritable magnetic charge ice,” that permits an unprecedented degree of control over local magnetic fields and could pave the way for new computing technologies. With potential applications involving data storage, memory and logic devices, magnetic charge ice could someday lead to smaller and more powerful computers or even play a role in quantum computing.
Current magnetic storage and recording devices, such as computer hard disks, contain nanomagnets with 2 polarities, each of which is used to represent either 0 or 1, binary digits. A magnetic charge ice system could have 8 possible configurations instead of 2, resulting in denser storage capabilities or added functionality unavailable in current technologies. “Our work is the first success achieving an artificial ice of magnetic charges with controllable energy states,” said Xiao, Argonne and NIU.
Over the past decade, scientists have been highly interested in creating, and attempting to manipulate properties of “artificial spin ices,” so-called as the spins have a lattice structure that follows the proton positioning ordering found in water ice.
Scientists consider artificial spin ices to be scientific playgrounds, where the mysteries of magnetism might be explored and revealed. However, in the past, researchers have been frustrated in their attempts to achieve global and local control of spin-ice magnetic charges. To overcome this, Xiao and his colleagues decoupled the lattice structure of magnetic spins and the magnetic charges. The scientists used a bi-axis vector magnet to precisely and conveniently tune the magnetic charge ice to any of 8 possible charge configurations. They then used a magnetic force microscope to demonstrate the material’s local write-read-erase multi-functionality at room temp. Eg. using a patterning technique, they wrote the word, “ICE,” on the material in a physical space 10 times smaller than the diameter of a human hair.
Magnetic charge ice is 2D and could be applied to other thin materials, such as graphene. It is environmentally friendly and relatively inexpensive to produce. “Although spin and magnetic charges are always correlated, they can be ordered in different ways,” said Wang, who now holds a joint appointment with Argonne and Notre Dame. “This work provides a new way of thinking in solving problems. Instead of focusing on spins, we tackled the magnetic charges that allow more controllability.”
There are hurdles yet to overcome before magnetic charge ice could be used in technological devices. Eg, a bi-axis vector magnet is required to realize all energy state configurations and arrangements, and it would be challenging to incorporate such a magnet into commercial silicon technology. But in addition to uses in traditional computing, quantum computing could benefit from magnetic monopoles in the charge ice. Other potential applications of magnetic charge ice might include enhancement of the current-carrying capability of superconductors. http://www.eurekalert.org/pub_releases/2016-05/niu-sc051616.php
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