When electrons sing in harmony

Quantum coherence – the ability of particles to move in synchrony like overlapping waves – is usually limited to exotic states such as superconductivity, where electrons pair up and flow coherently. In ordinary metals, collisions of the particles quickly destroy such coherence. But there is one metal that behaves differently.

In the kagome metal CsV₃Sb₅, after sculpting tiny crystalline pillars just a few micrometers across and applying magnetic fields, Aharonov–BohmA quantum-mechanical phenomenon in which an electrically charged particle is affected by an electromagnetic potential, despite being confined to a region in which both the magnetic field and electric field are zero. -like oscillations in electrical resistance are observed. The oscillations occur at regular intervals determined by the magnetic flux quantum that threads between adjacent layers of the metal.

A shared underlying mechanism

This phenomenon effectively transforms the material into a nanoscale Aharonov–Bohm interferometer, stacked vertically along the crystal structure. As a result, it demonstrates that electrons interfere collectively, even remaining coherent much longer than would be predicted by single-particle physics.

Several features reveal the cooperative nature of this effect. As the magnetic field angle is rotated, the oscillations abruptly switch between discrete frequencies rather than evolve smoothly. Even more strikingly, the coherence persists over distances longer than the electrons’ mean free path, ruling out an explanation based on independent particles bouncing through the crystal. The size of the oscillations is also telling: their amplitude closely matches other anomalous electronic responses previously reported in CsV₃Sb₅, hinting at a shared underlying mechanism that establishes intrinsic coherence in this material.

New research directions

Together, these findings shed new light on the still-debated correlated orders in kagome metals and position CsV₃Sb₅ as a rare platform where long-range coherent charge transport emerges without superconductivity. More broadly, they suggest that collective electronic coherence may be far more versatile – and widespread – than previously thought, opening new directions for exploring correlated quantum matter beyond conventional paradigms.

Figure: (a) illustration of long-range quantum coherence in a Kagome metal. (b) The temperature dependence of magnetoresistance oscillations demonstrates quantum-coherent transport at low temperatures.

You can find the full paper here: Many-body interference in kagome crystals

Principal investigators

Max Planck Institute for the Structure and Dynamics of Matter:

Chunyu Guo (Mark)
Philip J. W. Moll

Research contact at HFML-FELIX:

Steffen Wiedmann