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

Kim, Hyun‐Jin; Choi, Youngjoon; Lewandowski, Cyprian; Thomson, Alex; Zhang, Yiran; Polski, Robert; Watanabe, Kenji; Taniguchi, Takashi; Alicea, Jason; Nadj-Perge, Stevan

doi:10.48550/arxiv.2109.12127

Cited by 17 publications

(36 citation statements)

References 54 publications

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“…It should thus be possible to map out the stability of symmetry-breaking order with density, and correlate this order with the observed "cascade." Furthermore, since magic angle twisted trilayer graphene (MATTG) features the same symmetries and band topology [40][41][42], our conclusions apply to STM measurements [43,44] of MATTG mutatis mutandis.…”

Section: Su (2)mentioning

confidence: 57%

Detecting symmetry breaking in magic angle graphene using scanning tunneling microscopy

Hong,

Soejima,

Zaletel

2021

Preprint

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A growing body of experimental work suggests that magic angle twisted bilayer graphene exhibits a "cascade" of spontaneous symmetry breaking transitions, sparking interest in the potential relationship between symmetry-breaking and superconductivity. However, it has proven difficult to find experimental probes which can unambiguously identify the nature of the symmetry breaking.Here we show how atomically-resolved scanning tunneling microscopy can be used as a fingerprint of symmetry breaking order. By analyzing the pattern of sublattice polarization and "Kekulé" distortions in small magnetic fields, order parameters for each of the most competitive symmetry-breaking states can be identified. In particular, we show that the "Kramers intervalley coherent state," which theoretical work predicts to be the ground state at even integer fillings, shows a Kekulé distortion which emerges only in a magnetic field.

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Section: Su (2)mentioning

confidence: 57%

Detecting symmetry breaking in magic angle graphene using scanning tunneling microscopy

Hong,

Soejima,

Zaletel

2021

Preprint

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“…In particular, nodal superconductors are known to appear naturally in strongly correlated systems, including cuprate superconductors and heavy-fermion systems [1][2][3][4][5][6]. Van der Waals materials hosting superconducting states are well known [7-13], yet nodal monolayer van der Waals superconductors have remained elusive [14][15][16][17]. Here, we show that pristine monolayer 1H-TaS2 realizes a nodal superconducting state of f-wave spin-triplet symmetry.…”

mentioning

confidence: 80%

Evidence of nodal f-wave superconductivity in monolayer 1H-TaS$_2$ with hidden order fluctuations

Vaňo¹,

Ganguli²,

Amini³

et al. 2021

Preprint

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Unconventional superconductors represent one of the fundamental directions in modern quantum materials research. In particular, nodal superconductors are known to appear naturally in strongly correlated systems, including cuprate superconductors and heavy-fermion systems [1][2][3][4][5][6]. Van der Waals materials hosting superconducting states are well known [7-13], yet nodal monolayer van der Waals superconductors have remained elusive [14][15][16][17]. Here, we show that pristine monolayer 1H-TaS2 realizes a nodal superconducting state of f-wave spin-triplet symmetry. We show that including non-magnetic disorder drives the nodal superconducting state to a conventional gapped s-wave state. Furthermore, we observe the emergence of many-body excitations potentially associated to the unconventional pairing mechanism. Our results demonstrate the emergence of nodal superconductivity in a van der Waals monolayer, providing a building block for van der Waals heterostructures exploiting unconventional superconducting states.

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“…The effective value of α corresponding to a given non-interacting band structure is a nontrivial question, since the band velocity is generally renormalized upward by strong interactions. In TBG, empirical measurements of the Dirac velocity range between 7 × 10 4 m/s and 2 × 10 5 m/s near the magic angle [26][27][28]. Such velocities are significantly larger than the predictions of noninteracting theories, but still produce an estimate for α in the range 2 -6 (using r ≈ 5, which corresponds to a hexagonal boron nitride substrate).…”

Section: 𝑤 𝑎 ∼ 𝑛mentioning

confidence: 98%

Wigner crystallization at large fine structure constant

Joy,

Skinner

2021

Preprint

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We consider the fate of the Wigner crystal state in a two dimensional system of massive Dirac electrons as the effective fine structure constant α is increased. In a Dirac system, larger α naively corresponds to stronger electron-electron interactions, but it also implies a stronger interband dielectric response that effectively renormalizes the electron charge. We calculate the critical density and critical temperature associated with quantum and thermal melting of the Wigner crystal state using two independent approaches. We show that at α 1, the Wigner crystal state is best understood in terms of logarithmically-interacting electrons, and that both the critical density and the melting temperature approach a universal, α-independent value. We discuss our results in the context of recent experiments in twisted bilayer graphene near the magic angle.

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

Cited by 17 publications

References 54 publications

Detecting symmetry breaking in magic angle graphene using scanning tunneling microscopy

Detecting symmetry breaking in magic angle graphene using scanning tunneling microscopy

Evidence of nodal f-wave superconductivity in monolayer 1H-TaS$_2$ with hidden order fluctuations

Wigner crystallization at large fine structure constant

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