Quantum Matter Seminar by Dr. Yung-Yeh Chang on March 2, 2023

On March 2nd, 2023, the iTHEMS Quantum Matter Seminar was held online, featuring a talk on "Topological Kondo Superconductors" by Yung-Yeh Chang, a postdoctoral researcher at the National Center for Theoretical Sciences and National Yang Ming Chiao Tung University in Taiwan.

Yung-Yeh Chang began by introducing Kondo lattice and heavy fermion compound. Interestingly, superconductivity can emerge in this compound. Then, including topology, he proposed a realization of a 2D time-reversal symmetric superconductor in a class of Kondo lattice materials.

The proposed system involves the odd-parity Kondo hybridization, which mediates ferromagnetic spin-spin coupling and leads to spin-triplet resonant-valence-bond (t-RVB) pairing between local moments. The speaker explained that spin-triplet p±p' wave topological superconductivity is reached when the Kondo effect co-exists with t-RVB. By using the mean field theory to generate an effective free fermion (BdG) Hamiltonian, the topological nature was identified by the non-trivial topological invariant and the chiral Majorana modes at edges. The results on the superconducting transition temperature, Kondo coherent scale, and onset temperature of Kondo hybridization were discussed, which not only qualitatively but also quantitatively agree with the observations for UTe2.

In summary, the iTHEMS Quantum Matter Seminar on "Topological Kondo Superconductors," presented by Yung-Yeh Chang, provided an insightful discussion on the study of topological superconductors in Kondo lattice materials. The attendees had the opportunity to ask questions and engage in discussions with the speaker, making it an interactive and informative seminar.

Reported by Chen-Hsuan Hsu (Academia Sinica, Taiwan) and Ching-Kai Chiu