Atomic frustrated impurity states in Weyl metals

Mizobata, W. N.; Marques, Y.; Penha, Mariana Álvares; Sanches, J. E.; Ricco, L. S.; Souza, M. de; Shelykh, I. A.; Seridonio, A. C.

doi:10.1103/physrevb.102.075120

“…This scenario, indeed, approaches the corresponding present in the Weyl metals, as demonstrated in Ref. [31]. In the latter, a crossover can be observed from the ordinary molecular bonding and antibonding states, typically from the semimetallic Dirac phase [32,33], changing to atomic frustrated ones, upon breaking the inversion symmetry.…”

Section: Introductionsupporting

confidence: 67%

“…Panel (c): Band-structure for the untwisted system for the AA stacking, with coincident Dirac cones at the valley corners K = K arising from the top and bottom Brillouin zones of the monolayers, respectively. These Dirac points appear shifted in energy, due to the broken inversion symmetry in the metallic phase [28], in analogy to the metallic Weyl counterparts [31]. Panel (d): The twist restores the semimetallic character of the system, but now splits the Dirac points with K = K in momentum space by G θ = • , a crossover in the particle-hole symmetric profile in the spectral DOS for the dimer's atoms is observed.…”

Section: Introductionmentioning

confidence: 94%

“…We clarify that we designate our impurity dimer by "particle-hole symmetric molecule" in the entire text, just to label the regime where the molecular energy levels become symmetrical to the Fermi level (ω = 0). By introducing the molecule with charge mirror symmetry, we report here a phenomenon nonexistent in Weyl metals [31], which arise from Dirac semimetals and exhibit broken inversion symmetry. Particularly, the TBG nearly flat band Physics, characterized by an extremely low Fermi velocity, then rules the formation of a zero mode atomically frustrated, specially at a sweet spot, namely, the one given by the magic angle.…”

Section: Introductionmentioning

confidence: 96%

“…which should be of Weyl-metallic nature to emerge [31]. It means that just a pair of Dirac cones, with or without time-reversal symmetry broken, is not enough to provide the requirements to form the atomically frustrated state.…”

Section: Introductionmentioning

confidence: 99%

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Atomic frustration-based twistronics

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We theoretically investigate atomic frustrated states in diatomic molecules hosted by the bilayer graphene setup twisted by the first magic angle and with broken inversion symmetry in the Dirac cones of the system mini Brillouin zones. Such states show local spectral features typically from uncoupled atoms, but counterintuitively, they also exhibit nonlocal molecular correlations, which turn them into atomically frustrated. By considering a particle-hole symmetric molecule in the Moiré superlattice length-scale, we reveal distinctly from the metallic Weyl counterparts, a molecular zero mode atomically frustrated at the spectral densities of the dimer's atoms. To this end, a strong metallic phase with a plateau in the density of states established by the broken inversion symmetry, together with pronounced blue and red shifts in the molecular levels, due to the magic angle condition, should occur synergistically with atomic Coulomb correlations. Consequently, an entire collapse of these molecular peaks into a single one atomically frustrated, taking place exactly at the Fermi energy, becomes feasible just by tuning properly opposite gate voltages attached to the graphene monolayers. Therefore, we propose that unusual molecular bindings can be engineered via the twistronics of the bilayer graphene system, in particular, if its metallic phase is fully established.

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“…Two years after this theoretical work, Weyl points were experimentally observed in the microwave frequency range [8]. Following this first experimental demonstration, the realization of Weyl points has been achieved using photonic crystals [9,10,43,44,[55][56][57][58][59][60], phononic crystals [3,14,[61][62][63][64][65][66], metals [67][68][69][70] and semimetals [71][72][73][74][75][76][77].…”

Section: Band Degeneraciesmentioning

confidence: 97%

Nodal lines in momentum space: topological invariants and recent realizations in photonic and other systems

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Zhang³

et al. 2022

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Topological insulators constitute one of the most intriguing phenomena in modern condensed matter theory. The unique and exotic properties of topological states of matter allow for unidirectional gapless electron transport and extremely accurate measurements of the Hall conductivity. Recently, new topological effects occurring at Dirac/Weyl points have been better understood and demonstrated using artificial materials such as photonic and phononic crystals, metamaterials and electrical circuits. In comparison, the topological properties of nodal lines, which are one-dimensional degeneracies in momentum space, remain less explored. Here, we explain the theoretical concept of topological nodal lines and review recent and ongoing progress using artificial materials. The review includes recent demonstrations of non-Abelian topological charges of nodal lines in momentum space and examples of nodal lines realized in photonic and other systems. Finally, we will address the challenges involved in both experimental demonstration and theoretical understanding of topological nodal lines.

show abstract

Atomic frustration-based twistronics

Mizobata¹,

Sanches²,

Penha³

et al. 2021

2D Mater.

Self Cite

0

View full text Add to dashboard Cite

We theoretically investigate atomic frustrated states in diatomic molecules hosted by the bilayer graphene setup twisted by the first magic angle and with broken inversion symmetry in the Dirac cones of the system mini Brillouin zones. Such states show local spectral features typically from uncoupled atoms, but counterintuitively, they also exhibit nonlocal molecular correlations, which turn them into atomically frustrated. By considering a particle-hole symmetric molecule in the Moiré superlattice length-scale, we reveal distinctly from the metallic Weyl counterparts, a molecular zero mode atomically frustrated at the spectral densities of the dimer's atoms. To this end, a strong metallic phase with a plateau in the density of states established by the broken inversion symmetry, together with pronounced blue and red shifts in the molecular levels, due to the magic angle condition, should occur synergistically with atomic Coulomb correlations. Consequently, an entire collapse of these molecular peaks into a single one atomically frustrated, taking place exactly at the Fermi energy, becomes feasible just by tuning properly opposite gate voltages attached to the graphene monolayers. Therefore, we propose that unusual molecular bindings can be engineered via the twistronics of the bilayer graphene system, in particular, if its metallic phase is fully established.

show abstract

Atomic frustrated impurity states in Weyl metals

Cited by 6 publications

References 35 publications

Atomic frustration-based twistronics

Atomic frustration-based twistronics

Nodal lines in momentum space: topological invariants and recent realizations in photonic and other systems

Atomic frustration-based twistronics

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