Researchers have developed an organic-based magnet that can transport waves of quantum mechanical magnetization, known as magnons, and transform those waves into electrical signals, according to a new report in Nature Materials.
The new study is a significant development for the research of magnonics - electronic systems that use magnons rather than electrons. Until the new study, magnons had only been sent through difficult-to-handle inorganic materials. Using organic materials offers the chance to push magnonics research into an area that is more manageable, and therefore more promising, the study team said.
Existing electronics use electrons to transport information along wires. Magnons can also pass information, but rather than being made up of electrons, magnons are waves made from a quantum property known as spin. Changes in spin can be passed along in the same way that a charge can be passed down a wire. This phenomenon offers the possibility to transport information.
“You can think about magnonics like electronics,” study author Christoph Boehme, a physics professor at the University of Utah, said in a news release.“You have circuitry, and when you manage to build digital logic out of this, you can also build computers.”
At the moment, most magnonics scientists use yttrium iron garnet (YIG) as a wave carrier material. It’s costly and challenging to fabricate, particularly as a thin film or wire. Boehme said he gave up on using YIG because it was too problematic for his purposes.
For the new study, Boehme decided to investigate an organic magnet developed by his University of Utah colleague Joel Miller and see if it could be an alternative to YIG for magnonics purposes. The study team assessed the organic magnet for electron spin resonance (ESR), which indicates how long magnons can be sustained in the material. The researchers found that the narrowed the ESR line, the longer the magnons could be sustained.
The new study is based on a 2016 study Boehme co-authored that described how spin waves could be converted into electrical current through a phenomenon called the “inverse spin Hall effect,” and while the organic magnet does hold significant promise, it isn’t without challenges. The material, known as vanadium tetracyanoethylene or V(TCNE)x, is extremely sensitive to oxygen.
“If it’s freshly made, it’ll likely catch fire,” Miller said. “It’ll lose its magnetism.”
To reach their conclusion, the study team had to operate under low-oxygen conditions and perform an intricate, highly-choreographed series of actions, with each of the 14 study team members doing the right thing at the right time to move the process forward.
“Every time we carried out an experiment, everyone had to stand there and be ready on time to participate in this process,” Boehme said.
The process began with one team member preparing a precursor material at 4 a.m. and carried on continuously for two to three days. The process was also fraught with errors and missteps. For instance, the team realized a copper connecter used to transform magnons into electricity was reacting with V(TCNE)x and had to be replaced by a platinum connector.
Eventually, the team found that they could produce stable magnons in organic magnets and transfer spin waves into electrical signals; a significant step forward. The steadiness of the magnons in the V(TCNE)x was as effective as that in YIG.
The scientists said they hope this advance brings about more progress in replacing electronics since magnonic systems might be more compact and faster than existing systems. They would also have less heat loss and require much less energy.
The researchers also said other organic magnets could produce better results.
“There are many organic-based magnets,” Boehme said. “There’s no reason to believe that if you randomly pick one, it’s necessarily the best.
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