A recent study has discovered the "orbital Hall effect," a phenomenon that could significantly improve data storage in future computing devices. This discovery involves the generation of electrical energy from the orbital motion of electrons, providing potential advancements in the field of spintronics that will lead to more efficient, faster, and more reliable magnetic materials.
In a new breakthrough, researchers have used a new technique to confirm a previously undiscovered physical phenomenon that could be used to improve data storage in next-generation computing devices.
Spintronic memories used in advanced computers and satellites exploit magnetic states generated by the electrons' intrinsic angular momentum for data storage and retrieval. According to the physical movement of electrons, electron spin produces magnetic currents. This is known as the "spin Hall effect" and is a key application of magnetic materials in many different fields, from low-power electronics to fundamental quantum mechanics.
Recently, scientists have discovered that electrons can also generate electric current through a second kind of motion: orbital angular momentum, similar to the Earth's orbit around the Sun. This is called the "orbital Hall effect," said study co-author Roland Kawakami, a professor of physics at Ohio State University.
Theorists predict that by using light transition metals—materials with weaker spin Hall currents—magnetic currents generated by the orbital Hall effect will be easier to detect. But this study, led by physics graduate student Igor Lyalin and published in the journal Physical Review Letters, shows a way to observe this effect.
"Various Hall effects have been discovered for decades," Kawakami said. "But these orbital currents are really a new concept. The difficulty is that they are mixed with the spin currents in typical heavy metals, and it is difficult to distinguish them."
Instead, Kawakami's team demonstrated the orbital Hall effect by detecting the potential accumulation of orbital angular momentum of metal atoms by reflecting polarized light (in this case, laser light) onto various thin films of the light metal chromium. After nearly a year of painstaking measurements, the researchers detected clear magneto-optical signals, showing that electrons gathered at one end of the film exhibit strong orbital Hall effect characteristics.
"This successful detection could have a huge impact on future spintronics applications," he said. "The concept of spintronics has been around for about 25 years, and while it has been excellent in various memory applications, people are now trying to go further. One of the biggest goals in the field now is to reduce energy consumption, because this is the limiting factor in improving performance."
Reducing the total energy required for future magnetic materials to function well has the potential to enable lower power consumption, higher speeds and greater reliability, and help extend the life of the technology. Utilizing orbital currents instead of spin currents may save time and money in the long run.
The researchers note that this study opens the way to further understanding of how these strange physical phenomena occur in other kinds of metals, and they hope to continue to delve into the complex connection between the spin Hall effect and the orbital Hall effect.
Reference: "Magneto-optical detection of the orbital Hall effect in chromium" by Igor Lyalin, Sanaz Alikhah, Marco Berritta, Peter M. Oppeneer and Roland K. Kawakami, October 11, 2023, "Physical Review Letters".
DOI:10.1103/PhysRevLett.131.156702
Compiled source: ScitechDaily