In a recent study led by researchers from the Chinese Academy of Sciences and other international collaborators, a team of scientists has explored the intriguing properties of topological semimetals within iron-based superconductors. The research, published in the journal Nature Communications, sheds light on the potential of these materials for advanced energy applications.
The team, comprising Ze-Xian Deng, Qiang-Jun Cheng, Jing Jiang, and others, focused on the ferropnictide compound Ba(Fe$_{1-x}$Co$_x$)$_{2+δ}As$_2$. This compound has garnered attention for its superconducting properties and potential to host nontrivial topological states. The researchers combined angle-resolved magneto-transport measurements with first principles calculations to investigate the emergence and tunability of topological semimetal states in epitaxial films of this material.
Topological semimetals are known for their large, unsaturated magnetoresistance, which arises from ultrahigh carrier mobility and electron-hole compensation. However, these behaviors have not been well understood in the context of iron-based superconductors. The researchers found that the presence of interstitial iron atoms in the Ba(Fe$_{1-x}$Co$_x$)$_{2+δ}As$_2$ films plays a crucial role in modulating the topological semimetal states. These states exhibit ultralow residual resistivity and coexisting high-mobility electron and hole carriers, leading to linear positive magnetoresistance below 110 K.
One of the most remarkable findings is that the magnetoresistance becomes more pronounced when the magnetic field is applied parallel to the film plane, reaching an unsaturated value of 1206% at 56 Tesla. This significant magnetoresistance highlights the potential of these materials for applications in magnetic sensors and other energy-related technologies that require precise magnetic field measurements.
Furthermore, the researchers observed that superconductivity persists in these ferropnictide films, establishing them as a tunable platform for investigating the interplay among electron correlation, topology, and superconductivity. This coexistence of superconductivity and topological states opens up new avenues for exploring novel energy-efficient electronic devices and advanced energy storage solutions.
The study provides valuable insights into the fundamental properties of topological semimetals in iron-based superconductors and their potential applications in the energy sector. By understanding and harnessing these unique properties, researchers can pave the way for innovative technologies that leverage the interplay between topology and superconductivity for more efficient and sustainable energy solutions.
Source: Nature Communications
This article is based on research available at arXiv.