Carbon's lesson from a heavy friend

Article Physics, Multidisciplinary

Magic-Angle Twisted Bilayer Graphene as a Topological Heavy Fermion Problem

Zhi-Da Song et al.

Summary: Magic-angle twisted bilayer graphene exhibits seemingly contradictory localization and delocalization behaviors. By constructing a model, we are able to capture both aspects and provide a new perspective on strong correlation physics.

PHYSICAL REVIEW LETTERS (2022)

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Article Multidisciplinary Sciences

Artificial heavy fermions in a van der Waals heterostructure

Viliam Vano et al.

Summary: The study demonstrates the synthesis and characterization of a two-dimensional van der Waals heterostructure hosting artificial heavy fermions, providing a tunable platform for investigations of heavy-fermion physics. Using scanning tunnelling microscopy and spectroscopy, the researchers show that depending on the stacking order of the monolayers, either localized magnetic moments and the associated Kondo effect, or conduction electrons with a heavy-fermion hybridization gap can be revealed. The experiments realize an ultimately tunable platform for future experiments probing enhanced many-body correlations, dimensional tuning of quantum criticality and unconventional superconductivity in two-dimensional artificial heavy-fermion systems.

NATURE (2021)

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Article Multidisciplinary Sciences

Entropic evidence for a Pomeranchuk effect in magic-angle graphene

Asaf Rozen et al.

Summary: The study reveals a transition from a low-entropy electronic liquid to a high-entropy correlated state in magic-angle twisted bilayer graphene under the influence of electron density, temperature, and magnetic field. The correlated state demonstrates a unique combination of properties associated with itinerant electrons and localized moments, with distinct energy scales for different characteristics. The hybrid nature of the correlated state and the separation of energy scales have significant implications for the thermodynamic and transport properties of twisted bilayer graphene.

NATURE (2021)

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Article Multidisciplinary Sciences

Isospin Pomeranchuk effect in twisted bilayer graphene

Yu Saito et al.

Summary: The study explores the finite-temperature dynamics of spin and valley isospins in magic-angle twisted bilayer graphene, revealing a resistivity peak at high temperatures near a superlattice filling factor of -1, suggesting a Pomeranchuk-type mechanism. The data indicate the presence of a finite-field magnetic phase transition and a small isospin stiffness in the system.

NATURE (2021)

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Article Physics, Multidisciplinary

Emulating Heavy Fermions in Twisted Trilayer Graphene

Aline Ramires et al.

Summary: Twisted trilayer graphene can emulate heavy fermion physics by hosting extended and localized modes that can be controlled by interlayer bias. In the presence of interactions, local moments are developed and Kondo coupled to coexisting extended states. By electrically controlling the exchange between local moments, the system can transition from a magnetic to heavy fermion regime, allowing exploration of a generalized Doniach phase diagram.

PHYSICAL REVIEW LETTERS (2021)

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Review Physics, Applied

Quantum phases driven by strong correlations

Silke Paschen et al.

Summary: This article describes the new types of states of matter generated by strong correlations, including quantum criticality, superconductivity, and topological phases, and discusses their potential in quantum applications. Recent developments have shown that strong correlated systems are not always adiabatically connected to their non-interacting counterparts, and the quantum phases and fluctuations they create can defy traditional notions.

NATURE REVIEWS PHYSICS (2021)

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Article Multidisciplinary Sciences