dual superconducting states kagome lattice CsV₃Sb₅

Physicists Discover Dual Superconducting States in Kagome Lattice Material CsV₃Sb₅

Introduction to Superconductivity and Its Mystery

Superconductivity, characterized by the complete absence of electrical resistance at extremely low temperatures, is a quantum phenomenon of great interest. While the phenomenon is traditionally associated with the formation of Cooper pairs—electron pairs bound together—the precise factors that lead to superconductivity in quantum materials remain elusive.

Study on Kagome Lattice Superconductor CsV₃Sb₅

Researchers from Princeton University, the National High Magnetic Field Laboratory, Beijing Institute to Technology, and the University of Zurich recently undertook a study to explore the superconductivity of CsV₃Sb₅ a material with a Kagome lattice, which consists of atoms arranged in a hexagonal configuration resembling the traditional Kagome basket pattern.

The study, published in Nature Physics, establishes the presence of two superconducting regimes within this material, each linked to distinct transport and thermodynamic responses.

Discovery of Chiral Charge Density Wave in Kagome Superconductors

Excitement in the Quantum Materials Community

"In 2021, our identification of a chiral charge density wave in the Kagome superconductor AV₃Sb₅ (A = K, Rb, Cs) generated significant excitement within the quantum materials community," stated Shafayat Hossain, the study's first author, in an interview with the publishing website.

Interplay of Symmetry Breaking and Superconductivity

"Kagome superconductors exhibit multiple symmetry-breaking phenomena in the charge-ordered state before undergoing a transition to a superconducting ground state. Given the interplay between symmetry breaking, the multiband characteristics of AV₃Sb₅, and its topological band structure, the emergence of an unconventional superconducting state appeared highly probable."

Investigation into the Superconducting Nature of CsV₃Sb₅

Research Motivation and Methodology

When Hossain and his collaborators began exploring the origins of superconductivity in Kagome superconductors, existing literature provided no indication that the superconductivity in AV₃Sb₅ was unconventional. However, the intricate interplay of competing orders in the material's normal state suggested a possible impact on its superconducting behavior.

"Motivated by this, we employed transport and thermodynamic techniques to systematically explore the superconducting state CsV₃Sb₅," Hossain explained. "Unexpectedly, our initial transport measurements immediately revealed the presence of two distinct superconducting regimes, a discovery we had not foreseen."

Experimental Findings: Two Superconducting Regimes

Upper Critical Fields Across Temperature Variations

As part of their investigation, the researchers examined the upper critical fields of CsV₃Sb₅ across varying temperatures and for two distinct field orientations, specifically along the conducting planes and perpendicular to them.

Notably, the measurements revealed the existence of two distinct superconducting regimes in CsV₃Sb₅, delineated by a step-like enhancement in the upper critical fields.

Heat Capacity and Thermal Conductivity Observations

"Our observations revealed two distinct anomalies in the heat capacity as a function of temperature, signifying the emergence of two superconducting gaps," stated Luis Balicas, senior author of the study. "Furthermore, thermal conductivity exhibited a finite, constant contribution with temperature before the second gap formed, suggesting that certain regins of the Fermi surface remained ungapped in the superconducting state until further cooling induced gap formation in these electronic states."

Anisotropic Behavior and Unconventional Superconductivity 

Magnetic Field Rotation Effects on Thermal Conductivity

The researchers observed that when magnetic fields were rotated within the conducting planes, the thermal conductivity of the Kagome superconductor exhibited anisotropic behavior upon transitioning to a superconducting state.

This finding implies that the superconducting phase in CsV₃Sb₅ possesses a complex gap structure, suggesting a potential unconventional nature.

Gap Anisotropies and Pairing Symmetry

"Thermal conductivity is expected to be mediated by carriers excited across the superconducting gap, indicating a mildly anisotropic gap function," Balicas explained. "Interestingly, this anisotropy undergoes rotation upon the emergence of the second superconducting gap, suggesting distinct gap anisotropies. However, the precise pairing symmetry remains undetermined."

Implications of the Findings: Band-Selective Superconductivity

Presence of Multiple Superconducting Gaps

The results obtained by this research team suggest that the Kagome-lattice material CsV₃Sb₅ may exhibit band-selective superconductivity, a phenomenon where distinct electron bands develop independent superconducting gaps.

"While the precise symmetry of the gap function remains elusive, our study confirms the presence of multiple superconducting gaps in  CsV₃Sb₅ and suggests the potential existence of an unconventional pairing symmetry yet to be fully understood," said Balicas.

Charge Density Wave and Anomalous Hall Response

"The charge density wave (CDW) state, from which superconductivity emerges, exhibits unconventional characteristics. Notably, despite the absence of magnetism, it reportedly demonstrates an anomalous Hall response. Consequently, the coexistence of superconductivity with such a chiral CDW state suggests the likelihood of an unconventional pairing mechanism."

Future Research and Broader Impact on Superconductors

Significance of Kagome Superconductors in Quantum Research

The research conducted by Hossain, Balicas, and their team provides valuable insights into the superconducting behavior of CsV₃Sb₅, with potential implications for other Kagome-lattice superconductors. Their future studies will focus on further investigating multiband superconductors with intrinsic symmetry-breaking in their normal state.

"Kagome superconductors such as CsV₃Sb₅ are part of a broader class of materials, extending decades of research on cuprates and iron pnictides," Hossain stated. "The discovery of novel superconductors within this category remains an exciting frontier, as each new, material holds the potential to unveil unprecedented quantum states.

Exploring Topological Properties in Future Studies

"Our future research on Kgome superconductors will delve deeper into their unconventional gap structures and in-gap states, exploring the potential for nontrivial topological propterties."

Source

The discovery of two superconducting states in Kagome lattice materials opens new possibilities for quantum research and next-generation superconductors. Want to stay updated on groundbreaking scientific advancements?

• Read more cutting-edge science and tech news at FSNews365.
• Explore the latest in Human Health Issues.
• Understand how scientific discoveries impact our planet at Earth Day Harsh Reality.

Stay informed-follow these platforms for more insights into the future of technology and science!