Abstract Body

Considerable effort has recently been put into realizing metals built from kagome-based structural motifs due to their potential of hosting a number of unconventional, correlated (and sometimes topologically nontrivial) electronic states. This is due to the presence of multiple saddle points, Dirac points, and flat band features in their electronic band structures, which can naively be accessed by tuning their electron filling and Fermi energies. One recently discovered class of kagome metals of the form A V₃Sb₅ (A=K, Rb, Cs) possesses band structures wherein their V-based kagome lattices place saddle points and their resulting Van Hove singularities nearby/crossing the Fermi level. This seemingly stabilizes an array of unusual phase behaviors centered around a high-temperature charge density wave state and a low-temperature superconducting phase transition---select examples being hints of orbital antiferromagnetism, nematic instabilities, and pair density wave order. In this talk, I will give an overview of charge density wave order and superconductivity in this A V3Sb5 (A=K, Rb, Cs) class of kagome superconductors and motivate that the two transitions are intertwined in an unconventional manner. Particular focus will be given to insights that are gained when the Fermi level is tuned about the Van Hove points via chemical doping and via comparison to structurally-related cousins of the A V3Sb5 family. Comparisons to theoretical models of instabilities predicted for kagome metals tuned to their Van Hove points and future directions will be discussed.

References

[1] Linus Kautzsch and Yuzki M. Oey and Hong Li and Zheng Ren and Brenden R. Ortiz and Ram Seshadri and Jacob Ruff and Ziqiang Wang and Ilija Zeljkovic and Stephen D. Wilson, "Incommensurate charge-stripe correlations in the kagome superconductor CsV3Sb5-xSnx" [arxiv:2207.10608] npj quantum materials (in press).
[2] Linus Kautzsch, Brenden R. Ortiz, Krishnanand Mallayya, Jayden Plumb, Ganesh Pokharel, Jacob P. C. Ruff, Zahirul Islam, Eun-Ah Kim, Ram Seshadri, and Stephen D. Wilson “Structural evolution of the kagome superconductors AV3Sb5 (A = K, Rb, and Cs) through charge density wave order” Physical Review Materials 7, 024806 (2023).
[3] Brenden R. Ortiz, Andrea N. Capa Salinas, Miles J. Knudtson, Paul M. Sarte, Ganesh Pokahrel, and Stephen D. Wilson“Complete miscibility amongst the AV3Sb5 kagome superconductors: Design of mixed A-site AV3Sb5 (A: K, Rb, Cs) alloys” Physical Review Materials 7, 014801 (2023).
[4] Brenden R. Ortiz, Samuel M. L. Teicher, Linus Kautzsch, Paul M. Sarte, Noah Ratcliff, John Harter, Jacob P. C. Ruff, Ram Seshadri, and Stephen D. Wilson, “Fermi Surface Mapping and the Nature of Charge-Density-Wave Order in the Kagome Superconductor CsV3Sb5” Physical Review X 11, 041030 (2021).
[5] Brenden R. Ortiz, Paul M. Sarte, Eric M. Kenney, Michael J. Graf, Samuel M. L. Teicher, Ram Seshadri, and Stephen D. Wilson“Superconductivity in the Z2 kagome metal KV3Sb5” Physical Review Materials 5, 034801 (2021).
[6] Brenden R. Ortiz, Samuel M. L. Teicher, Yong Hu, Julia L. Zuo, Paul M. Sarte, Emily C. Schueller, A. M. Milinda Abeykoon, Matthew J. Krogstad, Stephan Rosenkranz, Raymond Osborn, Ram Seshadri, Leon Balents, Junfeng He, and Stephen D. Wilson “CsV3Sb5: A Z2 Topological Kagome Metal with a Superconducting Ground State” Physical Review Letters 125, 247002 (2020).
[7] Brenden R. Ortiz, Lídia C. Gomes, Jennifer R. Morey, Michal Winiarski, Mitchell Bordelon, John S. Mangum, Iain W. H. Oswald, Jose A. Rodriguez-Rivera, James R. Neilson, Stephen D. Wilson, Elif Ertekin, Tyrel M. McQueen, and Eric S. Toberer, “New kagome prototype materials: discovery of KV3Sb5, RbV3Sb5, and CsV3Sb5” Physical Review Materials 3, 094407 (2019).

Acknowledgment

This work was supported by the National Science Foundation (NSF) through Enabling Quantum Leap: Convergent Accelerated Discovery Foundries for Quantum Materials Science, Engineering and Information (Q-AMASE-i): Quantum Foundry at UC Santa Barbara (DMR-1906325)