Emergence of ferromagnetism at onset Kondo breakdown in moiré bilayer lattices

Physicists have reported the emergence of ferromagnetism at the onset of Kondo breakdown in moiré bilayer lattices, specifically in MoTe2/WSe2 structures. Moiré superlattices are formed by stacking two layers with slight rotational misalignment or lattice mismatch, while the Kondo lattice model describes the interaction between conduction electrons and localized magnetic impurities. Researchers from Cornell University and the National Institute for Materials Science in Japan synthesized these moiré Kondo lattices to explore their unique properties. Their findings, published in Nature Physics, indicate that as the density of itinerant carriers is tuned, a Kondo destruction transition occurs, leading to the emergence of a ferromagnetic Anderson insulator. This transition is characterized by simultaneous metal-to-insulator and magnetic quantum phase transitions, which is unexpected as previous studies typically reported antiferromagnetic correlations. The researchers aim to further investigate this phenomenon by adjusting the twist angle of the material to achieve higher critical densities, potentially revealing new exotic states of matter, including topological Kondo insulators. Their work opens new avenues for understanding Kondo physics and the behavior of heavy fermions in these engineered materials.

- Emergence of ferromagnetism observed in moiré Kondo lattices.

- Kondo destruction transition leads to ferromagnetic Anderson insulator.

- Simultaneous metal-to-insulator and magnetic phase transitions noted.

- Future research aims to explore higher critical densities and topological states.

- Study enhances understanding of heavy fermions and Kondo physics.