The fastest-possible electrical switching in magnetite, a naturally magnetic mineral has been clocked by researchers from the SLAC National Accelerator Laboratory. The results may push innovations in transistors used for controlling the flow of electricity across silicon chips and enable faster, more powerful computing devices.
Using SLAC’s Linac Coherent Light Source (LCLS) X-ray laser, researchers found that it takes only 1 trillionth of a second to flip the on-off electrical switch in samples of magnetite, which is thousands of times faster than in transistors now in use.
“This breakthrough research reveals for the first time the ‘speed limit’ for electrical switching in this material,”
said Stanford University researcher Roopali Kukreja, lead author of the recently published study. Magnetite (Fe3O4) is the oldest known magnetic material.
Next Generation Transistors
The LCLS experiment also established how the electronic structure of the sample rearranged into non-conducting islands surrounded by electrically conducting regions, which began to form just hundreds of quadrillionths of a second after a laser pulse struck the sample. The study shows how such conducting and non-conducting states can coexist and create electrical pathways in next-generation transistors.
The magnetite had to be cooled to minus 190 degrees Celsius to lock its electrical charges in place. The next step is to study more complex materials and room-temperature applications, said Kukreja. Future experiments will attempt to find exotic compounds and test new techniques to induce the switching and tap into other properties that are superior to modern-day silicon transistors.
The researchers have already conducted follow-up studies focusing on a hybrid material that exhibits similar ultrafast switching properties at near room temperature, which makes it a better candidate for commercial use than magnetite.
There are major global efforts underway to go past the limits of modern semiconductor transistors using new materials to satisfy demands for smaller and faster computers, according to Hermann Dürr, principal investigator of the LCLS experiment. LCLS has the distinctive ability to focus on processes that occur at the scale of atoms in trillionths and quadrillionths of a second.
Although magnetite’s basic magnetic properties have been known for thousands of years, the experiment shows how much still can be learned about the more exotic electronic properties of magnetite and other more complex materials using LCLS, said Dürr.
Reference: Speed limit of the insulator–metal transition in magnetite. S. de Jong et al. _Nature Material_s, 28 July 2013 (10.1038/NMAT3718)
