High-temp electrochemical memory; polymer data storage; magnetic states in antiferromagnets.
Researchers from the University of Michigan and Sandia National Laboratory propose a nonvolatile electrochemical memory that can store and rewrite information at temperatures over 1100°F (600°C), enabling it to continue working in environments as extreme as the surface of Venus.
Instead of transporting electrons, the memory moves oxygen ions between layered materials in a process similar to how a battery charges and discharges. The memory is made up of two layers, the semiconductor tantalum oxide and the metal tantalum, separated by a solid electrolyte. The oxygen ions are guided by a series of three platinum electrodes that control whether the oxygen is drawn into the tantalum oxide or pushed out of it.
“Once the oxygen atoms leave the tantalum oxide layer, a small region of metallic tantalum is left behind. At the same time, a tantalum oxide layer similarly caps the tantalum metal layer on the opposite side of the barrier. The tantalum and tantalum oxide layers do not mix, similar to oil and water, so these new layers will not revert back to the original state until the voltage is switched,” explained Derek Smith of the College of Engineering at U-M, in a press release. “Depending on the oxygen content of the tantalum oxide, it can act as either an insulator or a conductor—enabling the material to switch between two different voltage states that represent the digital 0s and 1s. Finer control of the oxygen gradient could enable computing inside the memory, with more than 100 resistance states rather than a simple binary. This approach could help reduce power demand.”
“So far, we’ve built a device that holds one bit, on par with other high-temperature computer memory demonstrations. With more development and investment, it could in theory hold megabytes or gigabytes of data,” said Yiyang Li, assistant professor of materials science and engineering at U-M, in a press release. The information states can be stored above 1100 °F for more than 24 hours. [1]
Researchers at Flinders University used a low-cost polymer made up of sulfur and dicyclopentadiene to store data at densities exceeding typical hard disk drives. An atomic force microscope and a scanning probe instrument were used to make and read small indentations in the material, which can be erased with short bursts of heat and reused several times.
“This research unlocks the potential for using simple, renewable polysulfides in probe-based mechanical data storage, offering a potential lower-energy, higher density and more sustainable alternative to current technologies,” said Abigail Mann, a PhD candidate from the College of Science and Engineering at Flinders University, in a statement. [2]
Researchers from Massachusetts Institute of Technology (MIT), Max Planck Institute, and Seoul National University created an longer-lasting magnetic state in an antiferromagnetic material using a terahertz laser. The laser’s oscillations are tuned to the natural vibrations among the material’s atoms, in a way that shifts the balance of atomic spins toward a new magnetic state.
“Antiferromagnetic materials are robust and not influenced by unwanted stray magnetic fields,” said Nuh Gedik, professor of physics at MIT, in a release. “However, this robustness is a double-edged sword; their insensitivity to weak magnetic fields makes these materials difficult to control.”
The researchers focused on FePS3, which transitions to an antiferromagnetic phase at 118K (-247° F). Using the terahertz pulse, the team was able to switch the cooled material to a magnetic state lasting several milliseconds even after the laser was turned off. Compared to previous light-induced phase transitions that lasted on the order of a picosecond, the new approach provides an extended window of time in which researchers can probe the properties of the temporary new state before it returns to antiferromagnetism. The team hopes this will aid in further studies trying to optimize antiferromagnets for use in next-generation memory storage technologies. [3]
[1] Li, J., Jalbert, A. J., Lee, S. et al. Nonvolatile electrochemical memory at 600°C enabled by composition phase separation. Device, 2024; 100623. http://dx.doi.org/10.1016/j.device.2024.100623
[2] Mann, A. K., Tonkin, S. J., Sharma, P. et al. Probe-Based Mechanical Data Storage on Polymers Made by Inverse Vulcanization. Adv. Sci. 2024, 2409438. https://doi.org/10.1002/advs.202409438
[3] Ilyas, B., Luo, T., von Hoegen, A. et al. Terahertz field-induced metastable magnetization near criticality in FePS3. Nature 636, 609–614 (2024). https://doi.org/10.1038/s41586-024-08226-x
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