Superconductivity and normal-state properties of kagome metal RbV3Sb5 single crystals

Abstract: We report the discovery of superconductivity and detailed normal-state physical properties of RbV3Sb5 single crystals with V kagome lattice. RbV3Sb5 single crystals show a superconducting transition at Tc ~ 0.92 K. Meanwhile, resistivity, magnetization and heat capacity measurements indicate that it exhibits anomalies of properties at T* ~ 102 - 103 K, possibly related to the formation of charge ordering state. When T is lower than T*, the Hall coefficient RH undergoes a drastic change and sign reversal from negative to positive, which can be partially explained by the enhanced mobility of hole-type carriers. In addition, the results of quantum oscillations show that there are some very small Fermi surfaces with low effective mass, consistent with the existence of multiple highly dispersive Dirac band near the Fermi energy level.

• The paper reveals a superconducting transition in RbV3Sb5 single crystals at approximately 0.92K.
• It employs resistivity, magnetization, heat capacity, and quantum oscillation measurements to uncover CDW-like anomalies near 102–103K.
• The findings indicate small Fermi pockets with low effective masses, suggesting the presence of multiple Dirac bands and topological superconductivity potential.

Superconductivity and Normal-State Properties of Kagome Metal RbV$_3$Sb$_5$ Single Crystals

The paper presents a comprehensive exploration of the physical properties of RbV$_3$Sb$_5$, a kagome metal known for its unique atomic lattice structure, comprised of vanadium atoms arranged selectively in two-dimensional planes. This kagome configuration is pivotal in dictating the electronic properties of the material, notably superconductivity alongside notable normal state properties. Herein, the authors detail their investigation into both the superconducting transition and the normal-state charge ordering phenomena, emphasizing the mixed behavior of superconductivity and charge-density wave (CDW)-like properties.

Experimental Findings

RbV$_3$Sb$_5$ single crystals exhibit a superconducting transition temperature ($T_c$) at approximately 0.92 K, highlighting its similarity to KV$_3$Sb$_5$ but notably lower than CsV$_3$Sb$_5$. This superconducting behavior coexists with distinct normal-state anomalies observed at $T^*\approx 102 - 103$ K. These anomalies are suggestive of a CDW-like state, particularly significant at this lattice composition. Critically, the Hall coefficient ($R_{\rm H}$) undergoes a marked change and sign inversion below $T^*$, indicative of changes to the charge carriers' properties, specifically the electron to hole-type transition. Similarly, resistivity, magnetization, and heat capacity measurements confirm the association of observed anomalies with charge ordering transitions.

Quantum Oscillations and Fermi Surface Features

The research utilizes Shubnikov-de Haas oscillations to probe the electronic structure, elucidating the presence of small Fermi surfaces that possess minimal effective masses. This observation is consistent with multiple Dirac bands proximate to the Fermi level, previously calculated and observed in related AV$_3$Sb$_5$ systems. These small Fermi pockets suggest a high degree of electron mobility, providing insight into the potential of RbV$_3$Sb$_5$ in hosting exotic electronic phenomena, such as those associated with Dirac or Weyl semimetals.

Theoretical and Practical Implications

The study contributes significantly to our understanding of how physical phenomena like superconductivity coexist with charge ordering in kagome materials. The interplay between electronic correlation, band topology, and charge density modulation is crucial in unraveling new quantum phases and potential applications in quantum computing and advanced electronic devices. Given the current findings and the material’s structural akinness to those observed in KV$_3$Sb$_5$ and CsV$_3$Sb$_5$, RbV$_3$Sb$_5$ emerges as another promising candidate for topological superconductivity.

Future Directions

Future inquiries into RbV$_3$Sb$_5$ could involve further exploration of its electronic phase diagram under varied experimental conditions, including strain, magnetic field, and chemical doping. Studies focusing on exploring unconventional superconductivity and its relation to the topological properties of this material may provide deeper insights into its potential quantum technological applications. This research opens pathways to assess not only the conditions facilitating such superconducting transitions but also the dynamic nature of the electronic carriers under these exotic interactions and structures.