Machine Learning Confirms Two New Superconductors, Accelerating Search for Room-Temperature Materials

An international research consortium, SuperC, has successfully demonstrated a machine-learning-guided pipeline to discover and experimentally confirm two new superconductors, YRu₃B₂ and LuRu₃B₂. Published in Physical Review Research, the study combines machine learning pre-screening with quantum geometry and density functional theory. The compounds, synthesized at Rice University, exhibit superconductivity below 1 K. Bulk superconductivity was rigorously verified using three independent measurement modalities to ensure scientific credibility.

Machine-learning superconductor discovery pipeline

• ▪The SuperC consortium developed a three-stage machine learning pipeline to screen and identify candidate superconducting materials
• ▪The SuperC consortium's pipeline uses machine-learning-based pre-screening followed by targeted density functional theory calculations to estimate critical temperatures
• ▪The SuperC consortium was founded in 2023 with the goal of discovering a room-temperature superconductor by 2033

YRu₃B₂ experimental confirmation

• ▪YRu₃B₂ exhibits a superconducting transition temperature of 0.81 K, confirmed through specific-heat measurements down to 60 mK
• ▪YRu₃B₂ was experimentally confirmed as a superconductor with a bulk superconducting volume fraction of approximately 100%

LuRu₃B₂ experimental confirmation

• ▪LuRu₃B₂ was initially overlooked by high-throughput predictions due to weakly imaginary modes in its computed phonon spectrum

Kagome lattice electronic structure

• ▪Kagome networks produce a flat electronic energy band where electrons have low kinetic energy, potentially facilitating Cooper pair formation
• ▪YRu₃B₂ and LuRu₃B₂ crystallize in a hexagonal CeCo₃B₂-type structure where ruthenium atoms form a planar kagome network

BCS theory Tc prediction

• ▪The electron-phonon coupling constant is 0.44 for YRu₃B₂ and 0.41 for LuRu₃B₂, placing both in the weakly coupled conventional BCS category
• ▪Density functional theory calculations predicted critical temperatures of 3.37 K for YRu₃B₂ and 1.88 K for LuRu₃B₂ using the Allen-Dynes formula

Superconductor verification standards

• ▪Superconductivity in YRu₃B₂ and LuRu₃B₂ was verified using three independent measurement modalities: magnetization, specific heat, and electrical transport
• ▪The measured London penetration depths for both YRu₃B₂ and LuRu₃B₂ are approximately 32 nm, agreeing with theoretical calculations