Advanced devices supporting applications in communications, clean energy, and aerospace require materials with improved thermal conductivity. In any case, to design materials with this property, researchers need to comprehend how phonons, or quantum units of the vibration of particles, act in a specific substance.
Fuyang Tay, a graduate student in applied physics who is working with the Rice Advanced Magnet with Broadband Optics (RAMBO), a tabletop spectrometer in Junichiro Kono’s laboratory at Rice University, stated, “Phonons are quite important for studying new materials because they govern several material properties such as thermal conductivity and carrier properties.” For instance, it is generally accepted that interactions between electrons and phonons lead to superconductivity.
“Phonons are very important in the study of new materials because they govern a variety of material properties, such as thermal conductivity and carrier properties.”
Fuyang Tay, a graduate student in applied physics working with the Rice Advanced Magnet with Broadband Optics (RAMBO),
“As of late, there has been developing interest in the attractive second conveyed by phonon modes that show round movement, otherwise called chiral phonons. However, the mechanisms that can result in a significant phonon-magnetic moment are unknown.
Andrey Baydin (left) and Fuyang Tay. Credit: Gustavo Raskosky/Rice University
A study describing the intricate connections between the magnetic properties of these quantum whirling dervishes and the underlying topology of the electronic band structure of a material, which determines the range of energy levels that electrons have within it, has been published by an international team led by Felix Hernandez from Brazil’s Universidade de So Paulo and Rice assistant research professor Andrey Baydin.
This finding adds to the growing body of knowledge about phonons and makes it possible to make better materials and manipulate phonons more effectively with magnetic fields.
In a past report, Baydin and colleagues applied an attractive field to lead telluride, a straightforward semiconductor material. At the point when they did as such, they saw that the phonons quit vibrating in a direct style and became chiral, moving in a round movement.
“Chiral phonons communicate with each other uniquely, in contrast to phonons that move directly,” Baydin said. “We could make use of these interactions if we knew how they work. Materials could be used in a variety of ways depending on their properties.”
The group wondered if altering the material’s topology—or electronic band structure—would have an effect on the material’s magnetic properties after observing that the magnetic moment of chiral phonons was quite small in the material they first focused on. A brand-new material known as a crystalline topological insulator was put through its paces by the researchers in order to provide an answer to this question.
Baydin stated, “We took the lead telluride and added tin to it.” Band inversion occurs when enough is added, resulting in topologically protected surface states. These materials are fascinating because, although they are insulating in bulk, they also have conducting electronic surface states, which is a very promising property that could be used in novel electronic devices.
Extra analyses uncovered that the chiral phononsmagnetic second was two significant degrees bigger in the topological material than in the material without such electronic geography.
“Our discoveries uncover convincing new experiences into the attractive properties of phonons in this material and underscore the complicated association between the attractive properties of chiral phonons and the material’s hidden electronic band structure geography,” Baydin said. He went on to say that the team intends to carry out additional experiments in the near future in order to gain a deeper comprehension of various aspects of phonon behavior.
Tay went on to say that these results, which show that topological materials have a significantly higher phonon magnetic moment, can help material scientists find and create materials with larger phonon magnetic moments for various device applications.
“This perception gives new insights into how to control phonon properties to change warm conductivity,” Tay said. “In addition, the interaction between electronic structure topology and chiral phonons raises the possibility of the phonons having an effect on the topological phase.
More information: Felix G. G. Hernandez et al, Observation of interplay between phonon chirality and electronic band topology, Science Advances (2023). DOI: 10.1126/sciadv.adj4074
