A research team from Yonsei University, Rutgers University, KAIST, and other institutes in South Korea has made a significant discovery in the field of condensed matter physics. They have found evidence of unconventional charge carriers in a Mott insulator at room temperature. Mott insulators are materials that should theoretically conduct electricity but instead behave as insulators due to the presence of strongly correlated electrons.
Traditionally, the unconventional excitations in Mott insulators have been believed to only exist at low temperatures. However, using terahertz time-domain spectroscopy techniques, the researchers observed in the Mott insulator terbium indium oxide (TbInO3) that the alternating current (a.c.) terahertz conductivity is proportional to the square of the frequency of light, even at room temperature.
This surprising finding challenges the long-standing belief that exotic excitations in Mott insulators can only be observed at low temperatures. The discovery of unconventional charge carriers, which are made up of a macroscopic number of quantum spins, provides new insights into the behavior of Mott insulators.
The researchers believe that their work could pave the way for further experiments and theoretical studies to better understand the fundamental physics behind these observations. Moreover, it could have implications for the development of fault-tolerant quantum computers that operate at room temperature.
The next steps for the research team include extending their investigations to other indium oxide compounds to search for similar effects. This research opens up new possibilities for exploring the properties of Mott insulators and advancing our knowledge of condensed matter physics.
Source: Taek Sun Jung et al, Unconventional room-temperature carriers in the triangular-lattice Mott insulator TbInO3, Nature Physics (2023). DOI: 10.1038/s41567-023-02174-5.