Spintronics refers to devices that utilize tiny magnetic properties alongside electric currents. These devices hold the promise of processing information at speeds comparable to traditional electronics, but with significantly lower energy consumption. A key question in advancing these technologies is how heating impacts their performance.
Spintronics refers to devices that utilize tiny magnetic properties alongside electric currents. These devices hold the promise of processing information at speeds comparable to traditional electronics, but with significantly lower energy consumption. A key question in advancing these technologies is how heating impacts their performance.
Researchers from the University of Illinois Urbana-Champaign have introduced a groundbreaking experimental method, as detailed in the journal APL Materials. This technique enables direct measurement of heating in spintronic devices, which facilitates comparisons with other influential factors. According to the researchers, this approach will help identify spintronic materials whose magnetic responses are less affected by thermal changes, ultimately leading to more efficient devices.
“Spintronic devices rely on the ability to alter magnetization using electric current, but there are two possible reasons for this: electromagnetic interactions with the current or the temperature increase resulting from the current,” explained Axel Hoffmann, the lead researcher and a professor of materials science and engineering at Illinois. “To enhance device performance, we need to grasp the fundamental physics at play, which is what our method has helped clarify.”
In contrast to traditional electronics, which utilize electrical signals to manage data and perform calculations, spintronics takes advantage of a fundamental electron property known as spin, leading to microscopic magnetic behaviors. These devices could operate with a fraction of the energy required by their electronic counterparts, attributable to their magnetic functionality. Some experts even propose that spintronics powered by fast electronics could offer the speed of conventional computers while remaining energy-efficient. “It’s akin to enjoying the advantages of both worlds,” Hoffmann noted.
The search for appropriate materials for these devices has proven challenging. Antiferromagnets have piqued interest due to their unique arrangement of opposing spins and reduced susceptibility to neighboring influence. For practical use in computing and memory applications, controlling the spin structure with electric current is essential. However, the substantial currents necessary for this manipulation can cause the temperature of the devices to rise, thereby introducing additional thermal effects that can impact spin structure along with electromagnetic influences.
“There is ongoing debate regarding whether the current itself causes changes in spin or if the ensuing heating is primarily responsible,” said Hoffmann. “If the current is the main driver, it’s relatively straightforward to achieve fast responses. Conversely, if the effects are driven by heat, factors such as thermal conductance and relaxation could restrict the device’s operating speed. Therefore, the device’s exact functioning hinges on the underlying physics at play.”
Previous attempts to investigate the significance of current versus temperature-driven influences were limited by the challenge of measuring heating effects in small devices directly. Myoung-Woo Yoo, a postdoctoral researcher in Hoffmann’s team, developed an experimental approach where thermal effects were analyzed by observing how devices heat substrates with varying thermal conductivities.
“We created antiferromagnetic samples on silicon dioxide substrates with varying thicknesses,” said Yoo. “Thicker substrates have lower heat conductivity, which means that antiferromagnets on these samples experience higher temperatures under the same electric current. If device heating substantially contributes to changes in spin structure, we would expect to see differences across devices on different substrates.”
The researchers discovered that heating considerably affected the antiferromagnet Mn3Sn, but acknowledged that there are many other antiferromagnetic materials suitable for spintronics. Their method lays the groundwork for systematically evaluating the impact of heating relative to electric current effects.
“We now have a clear strategy to evaluate the role of electric heating in spintronic devices,” Yoo stated. “Moreover, this methodology is broadly applicable, meaning it can be utilized for various systems, including conventional electronics. This approach can enhance the functionality of any kind of micro-scale device.”
