In the realm of energy materials research, a team of scientists from the Indian Institute of Science Education and Research (IISER) Kolkata has made a significant discovery that could potentially impact the energy sector. The researchers, led by Dr. Mintu Mondal, have uncovered a previously unknown phase transition in a unique material called (TaSe4)2I, a type of Weyl semimetal that exhibits a charge density wave (CDW) transition.
The team, including Sk Kalimuddin, Sudipta Chatterjee, Arnab Bera, Satyabrata Bera, Deep Singha Roy, Soham Das, Tuhin Debnath, Ashis K. Nandy, and Shishir K. Pandey, employed a combination of low-frequency resistance noise spectroscopy, electrical transport, and thermoelectric measurements to investigate the properties of (TaSe4)2I. Their findings, published in the journal Nature Communications, reveal that this material undergoes an additional phase transition at a much lower temperature than the initial CDW transition.
The initial CDW transition in (TaSe4)2I occurs at around 263 Kelvin, but the researchers discovered a hidden-order phase transition at approximately 100 Kelvin. This transition is characterized by a sharp increase in the noise exponent and variance of resistance fluctuations, indicating a change in the material’s electronic behavior. The team also observed a pronounced anomaly in the Seebeck coefficient near this transition temperature, suggesting a reconstruction of the Fermi surface, which is the boundary between occupied and unoccupied electronic states in a material.
To understand the underlying mechanism of this transition, the researchers performed first-principles calculations. They found that the material undergoes a structural distortion from a high-symmetry phase to a low-symmetry phase, passing through an intermediate symmetry phase. This distortion leads to a renormalization of the electronic structure near the Fermi level and the opening of a bandgap in the hidden-order phase.
The practical implications of this research for the energy sector are significant. Weyl semimetals like (TaSe4)2I are known for their unique electronic properties, which could be harnessed for advanced electronic and energy applications. The discovery of this hidden-order phase transition enriches the phase diagram of the material and provides a new platform for studying the interplay between electronic and structural orders. This understanding could lead to the development of new materials with tailored electronic properties for applications in thermoelectrics, spintronics, and other energy-related technologies.
In summary, the research team from IISER Kolkata has uncovered a novel phase transition in a Weyl semimetal that could have important implications for the energy sector. Their findings highlight the potential of advanced materials research to drive innovation in energy technologies.
This article is based on research available at arXiv.