Emulating Heavy Fermions in Twisted Trilayer Graphene

Ramires, Aline; Lado, José L.

doi:10.1103/physrevlett.127.026401

Cited by 59 publications

(27 citation statements)

References 83 publications

(117 reference statements)

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“…The positive and negative voltage dips are typically symmetric in energy, independent of filling-ruling out the possibility that the dip-hump structure is intrinsic to background density of states. Similar dip-hump features are observed spectroscopically in a range of both conventional strongly coupled phonon superconductors 32,33 as well as unconventional cuprate, iron-based and heavy fermion superconductors [34][35][36][37][38][39] . Such features are usually interpreted as a signature of bosonic modes that mediate superconductivity and can thus provide key insight into the pairing mechanism 40,41 .…”

supporting

confidence: 54%

Spectroscopic Signatures of Strong Correlations and Unconventional Superconductivity in Twisted Trilayer Graphene

Kim¹,

Choi²,

Lewandowski³

et al. 2021

Preprint

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supporting

confidence: 54%

Spectroscopic Signatures of Strong Correlations and Unconventional Superconductivity in Twisted Trilayer Graphene

Kim¹,

Choi²,

Lewandowski³

et al. 2021

Preprint

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“…However, without magnetic field, these Dirac cone electrons are itinerant and therefor may interact with localized flat band electrons via magnetic interactions such as Kondo scattering. 44 This is also possibly responsible for the gapped states at displacement field that is smaller than 𝐷 (𝜈) for integer filling 𝜈 = 2 reported previously. 45 Such candidate heavy fermion state in MATTG requires further studies on localized magnetic moments in flat band at these integer fillings.…”

Section: 𝑫-Induced Phase Transitionsmentioning

confidence: 75%

Dirac cone spectroscopy of strongly correlated phases in twisted trilayer graphene

Cheng

Ledwith

Watanabe

et al. 2022

Preprint

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Mirror-symmetric magic-angle twisted trilayer graphene (MATTG) hosts flat electronic bands close to zero energy, and has been recently shown to exhibit abundant correlated quantum phases with flexible electrical tunability.1–3 However studying these phases proved challenging as these are obscured by intertwined Dirac bands. In this work, we demonstrate a novel spectroscopy technique, that allows to quantify the energy gaps and Chern numbers of the correlated states in MATTG by driving band crossings between Dirac cone Landau levels and the energy gaps in the flat bands. We uncover hard correlated gaps with Chern numbers of C = 0 at integer moiré unit cell fillings of ν = 2 and 3 and reveal novel charge density wave states originating from van Hove singularities at fractional fillings of ν = 5/3 and 11/3. In addition, we demonstrate the existence of displacement field driven first-order phase transitions at charge neutrality and half fillings of the moiré unit cell ν = ± 2, which is consistent with a theoretical strong-coupling analysis, implying the breaking of the C2T symmetry. Overall these properties establish the diverse and electrically tunable phase diagram of MATTG and provide an avenue for investigating electronic quantum phases and strong correlations in multiple-band moiré systems.

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“…Their potential for correlated physics stems from the vanishing electronic dispersion, which creates a greatly enhanced density of states at the Fermi energy [17][18][19][20]. While a wide variety of correlated states in flat band systems can emerge, minimal attractive or repulsive on-site interactions are well known to lead to magnetism and superconductivity, respectively [2,[21][22][23][24][25][26][27]. More complex interactions in flat bands are also well known to give rise to other symmetry broken states, including charge density waves and bond orders [28][29][30][31].…”

Section: Introductionmentioning

confidence: 99%

Kondo-lattice-mediated interactions in flat band systems

Kumar,

Chen,

Lado

2021

Preprint

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Electronic flat bands represent a paradigmatic platform to realize strongly correlated matter due to their associated divergent density of states. In common instances, including electron-electron interactions leads to magnetic instabilities for repulsive interactions and superconductivity for attractive interactions. Nevertheless, interactions of Kondo nature in flat band systems have remained relatively unexplored. Here we address the emergence of interacting states mediated by Kondo lattice coupled to a flat band system. Combining dynamical mean-field theory and tensor networks methods to solve flat band Kondo lattice models in one and two dimensions, we show the emergence of a robust underscreened regime leading to a magnetically ordered state in the flat band. Our results put forward flat band Kondo lattice models as a platform to explore the genuine interplay between flat band physics and many-body Kondo screening.

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Emulating Heavy Fermions in Twisted Trilayer Graphene

Cited by 59 publications

References 83 publications

Spectroscopic Signatures of Strong Correlations and Unconventional Superconductivity in Twisted Trilayer Graphene

Spectroscopic Signatures of Strong Correlations and Unconventional Superconductivity in Twisted Trilayer Graphene

Dirac cone spectroscopy of strongly correlated phases in twisted trilayer graphene

Kondo-lattice-mediated interactions in flat band systems

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