Kagome metals, known for their distinctive two-dimensional lattices formed by corner-sharing triangles, have drawn significant attention in condensed matter physics due to their unique electronic properties.
Recent theoretical predictions suggest that these materials can host compact molecular orbitals – standing-wave patterns of electrons – that may enable unconventional superconductivity and unusual magnetic orders when activated by electron correlation effects. In most kagome materials, these flat electronic bands lie too far from active energy levels to meaningfully influence behavior.
However, in CsCr₃Sb₅, researchers have found that the flat bands are actively involved, directly affecting the material’s superconducting and magnetic properties, making it a rare platform for studying quantum phenomena.
New pathway to engineer exotic superconductivity
A recent study, led by Pengcheng Dai, Ming Yi, and Qimiao Si of Rice University’s Department of Physics and Astronomy and Smalley-Curl Institute, along with Di-Jing Huang from Taiwan’s National Synchrotron Radiation Research Center, has been focusing on the chromium-based kagome metal CsCr₃Sb₅.
Published in Nature Communications, the research examines how this material, which exhibits superconductivity under pressure, hosts active flat electronic bands that directly influence its quantum properties, offering new insights into the design of unconventional superconductors and other advanced quantum materials.
According to the researchers, their findings confirm a surprising theoretical prediction and highlight a pathway for engineering exotic superconductivity through chemical and structural control.
The study also provides direct evidence that active flat electronic bands in CsCr₃Sb₅ can be manipulated to influence the material’s superconducting and magnetic properties, offering a new platform for exploring unconventional quantum behaviors and guiding the design of next-generation quantum materials.
Proof shows kagome lattice geometry controls electron behavior
The experimental evidence now confirms concepts that until recently existed only in theoretical models, demonstrating that the unique geometry of kagome lattices can serve as a precise tool for controlling electron behavior in solids. Additionally, gathering such detailed data depended on exceptionally large and high-purity crystals of CsCr₃Sb₅, produced through a refined synthesis method that yielded samples roughly 100 times bigger than those achieved in earlier studies, the scientists noted.
The research team also combined advanced synchrotron techniques with theoretical modeling to probe active standing-wave electron modes. Using angle-resolved photoemission spectroscopy (ARPES), they mapped electrons emitted under synchrotron light, revealing distinct signatures of compact molecular orbitals.
Resonant inelastic X-ray scattering (RIXS) further captured magnetic excitations tied to these electronic states, providing a comprehensive view of how lattice geometry governs emergent quantum phenomena.
Furthermore, the ARPES and RIXS results indicate that the flat bands in CsCr₃Sb₅ actively participate in shaping the material’s magnetic and electronic properties, rather than remaining passive. Theoretical analysis supported these findings by examining the effects of strong electron correlations using a custom-built lattice model, which successfully reproduced the observed features and guided the interpretation of experimental results.