New preprint: Pseudo-spin-polarized topological superconductivity in kagome RbV3Sb5
Our preprint Pseudo-spin-polarized topological superconductivity in kagome RbV3Sb5 develops a microscopic interpretation of the unusual magnetic response observed in superconducting RbV3Sb5. The work connects experimental constraints from our transport studies with a concrete theory of odd-parity nodal topological superconductivity.
Why this matters
Magnetic hysteresis in a superconductor strongly restricts the possible pairing states, but the kagome electronic structure, spin-orbit coupling, and nematic symmetry make a simple spin-only description insufficient. A successful theory must explain the in-plane magnetic response, the existence of superconducting domains, and the nodal character of the gap within one consistent framework.
Key findings
The study constructs an eight-band model for the nematic normal state of RbV3Sb5 and projects it onto a symmetry-respecting pseudo-spin basis near the Fermi surface. Within this framework, the proposed order parameter has odd parity and is both nonunitary and pseudo-spin-polarized. Domains with opposite pseudo-spin polarization respond differently to an applied magnetic field, naturally producing the experimentally observed hysteresis and unequal critical fields.
The proposed phase is also predicted to be a nodal topological superconducting state. The system’s boundary is predicted to host Majorana flat-band modes, providing a direct experimental target for tunneling spectroscopy. The model therefore connects a bulk transport signature to a boundary-state prediction.
LinLab’s role
Dr. Ben-Chuan LIN served as a corresponding author and brought the decisive experimental constraints from our RbV3Sb5 transport program into the theoretical analysis. In particular, the field-sweep hysteresis, current-induced state resetting, nematic symmetry, and comparison with CsV3Sb5 were used to narrow the allowed pairing scenarios. This experiment-driven approach ensures that the proposed state addresses several observations simultaneously rather than explaining a single isolated feature.
Collaboration and outlook
The theoretical framework was developed with Professor Kam Tuen Law’s group at the Hong Kong University of Science and Technology. The work provides testable directions for spin-sensitive and tunneling experiments, and it offers a route to connect kagome superconductivity with Majorana boundary physics and topological quantum states.