Electrically tunable heavy fermion and quantum criticality in magic-angle twisted trilayer graphene

TL;DR

This paper demonstrates electrically tunable heavy fermion states and quantum criticality in magic-angle twisted trilayer graphene, revealing a controllable quantum phase transition with potential for exploring unconventional superconductivity.

Contribution

It provides the first direct evidence of electrically tunable heavy fermion behavior and quantum criticality in moire superlattices, expanding the platform for correlated quantum phases.

Findings

Observation of a quantum phase transition from antiferromagnetic semimetal to heavy fermion metal.

Evidence of Fermi surface reconstruction near the quantum critical point.

Significant enhancement of quasiparticle effective mass near criticality.

Abstract

The interplay between localized magnetic moments and itinerant electrons gives rise to exotic quantum states in condensed matter systems. Two-dimensional moire superlattices offer a powerful platform for engineering heavy fermion states beyond conventional rare-earth intermetallic compounds. While localized and itinerant carriers have been observed in twisted graphene moire systems, direct evidence of their strong coupling--leading to artificial heavy fermion states--has remained elusive. Here, we demonstrate electrically tunable heavy fermion in magic-angle twisted trilayer graphene, achieved by controlling the Kondo hybridization between localized flatband electrons and itinerant Dirac electrons via a displacement field. Our results reveal a continuous quantum phase transition from an antiferromagnetic semimetal to a paramagnetic heavy fermion metal, evidenced by a crossover from logarithmic to quadratic temperature-dependent resistivity, a dramatic enhancement of quasiparticle effective mass, and Fermi surface reconstruction near quantum critical point. This highly tunable platform offers unprecedented control over heavy fermion physics, establishing moire heterostructures as a versatile arena for exploring correlated quantum phases--including potential unconventional superconductivity--in two-dimensional materials.