Magnetism is everywhere around us—even if we rarely stop to think about it. It’s in your earbuds, your laptop, your MRT gates. And all of it works because electrons, the tiny particles that zip through our devices, carry their own miniature magnets.
But electrons have two tricks up their sleeves. They spin on the spot like tiny tops, and they also orbit their atom’s nucleus. Most magnets rely heavily on that spin action, but a group of scientists has now found a way to tap into the lesser-used orbital side using a material called thulium iron garnet (TmIG).
“In most common magnets, spin is the main source of magnetism, but in certain elements such as rare-earths, the orbital contribution becomes strong,” explained James Lourembam, a Senior Scientist at the A*STAR Institute of Materials Research and Engineering (A*STAR IMRE).
“By understanding how orbital and spin moments interact, we can engineer materials with tailor-made magnetic behaviours, laying the groundwork for ‘orbitronic’ devices, which can utilise this orbital moment to transmit information,” said Ganesh Ji Omar, first author of the study.
Lourembam and his team studied TmIG, which belongs to the same family as another material already used in modern radar and communications technologies. Together with collaborators from the National University of Singapore and the ALBA Synchrotron in Spain, the researchers subjected the rare-earth material to temperature changes and crystal modifications to better understand its magnetic behaviour.
They examined how electron spins collectively ‘resonate’ under a magnetic field at room temperature, finding this response unusually low for TmIG compared to other common magnets where spin magnetism predominates. This property decreased further upon cooling, indicating TmIG’s strong orbital magnetic moment that competes with the usual spin magnetism. Inspired by this unexpected finding, the researchers probed individual elements in the compound. Comparing the findings between collective and individual measurements allowed them to determine the specific contributions of orbital and spin moments.
“This tuneable orbital magnetism acts as a control knob; it will allow us to precisely adjust the speed and efficiency at which magnetic information is transmitted,” said Lourembam. “Our work highlights the unexplored f-orbital magnetism in the rare-earths, opening new ways to design materials where orbital magnetism can be used for practical technologies.”
By gaining a deeper understanding of the magnetic properties of rare-earths, the team hopes their findings can eventually support the incorporation of these elements into novel materials for various devices. For example, they may be used to build microelectronic magnetic insulators, where magnetic signals travel without the use of electric currents that generate much heat. Reducing wasted heat can lead to more energy-efficient technologies with less power loss.
“Moving forward, we aim to exploit these rare-earth magnets for applications such as mmWave communications, optoelectronics and microwave devices,” said Lourembam.
The A*STAR-affiliated researchers contributing to this research are from the A*STAR Institute of Materials Research and Engineering (A*STAR IMRE).
