Anomalous electrons in a metallic kagome ferromagnet

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• Ordinary metals exhibit Fermi liquid behavior where electrons act non-interacting.
• Some materials defy this description due to strong electron-electron interactions, often linked to specific lattice structures.
• Understanding these non-Fermi liquid states is crucial for novel electronic properties.

Purpose of the Study:

• To investigate non-Fermi liquid behavior in the ferromagnetic kagome metal Fe3Sn2.
• To identify the electronic structure and interaction mechanisms responsible for deviations from Fermi liquid theory.
• To explore the role of flat bands in emergent electronic phenomena.

Main Methods:

• Spectroscopy was employed to probe the electronic states of Fe3Sn2.
• Density functional theory calculations were used for comparison and band structure prediction.
• Analysis focused on electron pockets and band fractionalization at low temperatures.

Main Results:

• Spectroscopy revealed non-Fermi liquid behavior in Fe3Sn2.
• Three C3-symmetric electron pockets were observed at the Brillouin zone center.
• A third, sharply defined band emerged via fractionalization, indicating strong electron-electron interactions and a nearby flat band.

Conclusions:

• Fe3Sn2 exhibits non-Fermi liquid behavior attributed to strong electron interactions and flat bands.
• The fractionalization of electron bands provides evidence for emergent many-body physics.
• This discovery opens new avenues for studying flat band physics arising from lattice geometry versus atomic orbitals.