Chiral Phonons: Unlocking Efficient and Affordable Orbitronic Devices
In a groundbreaking study, an international team of researchers has discovered a novel way to harness the power of chiral phonons for generating orbital current without the need for magnetic elements. This achievement is made possible by the inherent magnetic moments of chiral phonons, and it can be realized in common crystal materials. The research holds immense potential for the development of cost-effective and energy-efficient orbitronic devices, revolutionizing the electronics industry.
The foundation of all electronic devices lies in the charge of an electron, which possesses three fundamental properties: spin, charge, and orbital angular momentum. While spin has been extensively explored as a means to create current, the field of orbitronics, which utilizes an electron's orbital angular momentum to generate current, is relatively new. Traditionally, generating orbital current has been technically challenging, requiring the injection of charge current into specific transition metals, many of which are classified as critical materials essential for energy technologies and national security.
Dali Sun, a professor of physics and member of the Organic and Carbon Electronics Lab (ORaCEL) at North Carolina State University, explains, "Traditionally, generating orbital currents has been a complex task. However, our research demonstrates a novel approach where we use a heat gradient to drive chiral phonons in a quartz (SiO2) substrate. These chiral phonons, with their own magnetic moments, can be converted into orbital current."
The study builds upon previous research, which found that spin current can be created and controlled by applying a thermal gradient to non-magnetic hybrid semiconductors containing chiral phonons. Chiral phonons are groups of atoms that move in a circular direction when excited by an energy source like heat, propagating their angular momentum through the material.
Jun Liu, an associate professor of mechanical and aerospace engineering at NCState and a member of ORaCEL, adds, "In this study, we've shown that we can harness the angular momentum of chiral phonons and convert it into orbital current instead of spin. This can be achieved in simple non-magnetic insulators containing chiral phonons, as the rotation of these phonons generates magnetism."
The researchers are optimistic that this breakthrough will pave the way for cost-effective orbitronic applications. Dali Sun further emphasizes, "This work not only addresses fundamental questions about the interplay between structural chirality and orbital currents but also has the potential to expand the field of orbitronics significantly."
The research findings have been published in Nature Physics and are available online. Jun Zhou, a physicist at Nanjing Normal University, is a co-corresponding author. Yoji Nabei, a postdoctoral researcher in Sun's group, is the first author. The study was supported by the Department of Energy and the Air Force Office of Scientific Research, Multidisciplinary University Research Initiatives (MURI) Program.
This groundbreaking research opens up exciting possibilities for the future of electronics, offering a more sustainable and affordable approach to orbitronic devices.
