scholarly journals Interacting bosons in two-dimensional flat band systems

2015 ◽  
Vol 88 (8) ◽  
Author(s):  
Petra Pudleiner ◽  
Andreas Mielke
Keyword(s):  
Flat Band ◽  
Two Dimensional

scholarly journals Extremely flat band in bilayer graphene

2018 ◽  
Vol 4 (11) ◽  
pp. eaau0059 ◽  
Author(s):  
D. Marchenko ◽  
D. V. Evtushinsky ◽  
E. Golias ◽  
A. Varykhalov ◽  
Th. Seyller ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Bilayer Graphene ◽  
Flat Band ◽  
Honeycomb Lattice ◽  
Band Model ◽  
Two Dimensional ◽  
Band Formation ◽  
Constant Energy ◽  
Mexican Hat ◽  
Band Dispersion

We propose a novel mechanism of flat band formation based on the relative biasing of only one sublattice against other sublattices in a honeycomb lattice bilayer. The mechanism allows modification of the band dispersion from parabolic to “Mexican hat”–like through the formation of a flattened band. The mechanism is well applicable for bilayer graphene—both doped and undoped. By angle-resolved photoemission from bilayer graphene on SiC, we demonstrate the possibility of realizing this extremely flattened band (< 2-meV dispersion), which extends two-dimensionally in a k-space area around the K¯ point and results in a disk-like constant energy cut. We argue that our two-dimensional flat band model and the experimental results have the potential to contribute to achieving superconductivity of graphene- or graphite-based systems at elevated temperatures.

Two-Step Evolution of the Quasiparticle Band with Doping in the Two-Dimensional t-t′-t″-J Model

1998 ◽  
Vol 12 (29n31) ◽  
pp. 2914-2919
Author(s):  
Chang-De Gong ◽  
Wei-Guo Yin ◽  
P. W. Leung
Keyword(s):  
Theoretical Analysis ◽  
Excellent Agreement ◽  
Exact Diagonalization ◽  
Flat Band ◽  
Two Dimensional ◽  
Doping Dependence ◽  
Flat Region ◽  
Half Filling ◽  
Quasiparticle Band

We study the doping dependence of photoemission spectra for the t-t′-t″-J model by using the exact diagonalization technique and present a consistent theoretical analysis. Both calculations show that upon doping the enhancement of incoherent motion of holes due to the t′ and t″ terms accounts for the formation of the flat region around (π,0) in the quasiparticle dispersion at underdoped and optimally doped region, despite the absence of the flat band at half filling. Our results are in excellent agreement with resent photoemission experiments on Bi 2 Sr 2 Ca 1 Cu 2 O 8+δ [Marshall et al., Phys. Rev. Lett.76, 4841 (1996)] and Sr 2 CuO 2 Cl 2 [Wells et al., Phys. Rev. Lett.74, 964 (1995)].

scholarly journals Kagome van-der-Waals Pd3P2S8 with flat band

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Seunghyun Park ◽  
Soonmin Kang ◽  
Haeri Kim ◽  
Ki Hoon Lee ◽  
Pilkwang Kim ◽  
...  
Keyword(s):  
Diamagnetic Susceptibility ◽  
Van Der Waals ◽  
Localized States ◽  
Flat Band ◽  
Two Dimensional ◽  
Kagome Lattice ◽  
Kagomé Lattice ◽  
Localized State ◽  
Low Dimensional ◽  
Important Structure

AbstractWith the advanced investigations into low-dimensional systems, it has become essential to find materials having interesting lattices that can be exfoliated down to monolayer. One particular important structure is a kagome lattice with its potentially diverse and vibrant physics. We report a van-der-Waals kagome lattice material, Pd3P2S8, with several unique properties such as an intriguing flat band. The flat band is shown to arise from a possible compact-localized state of all five 4d orbitals of Pd. The diamagnetic susceptibility is precisely measured to support the calculated susceptibility obtained from the band structure. We further demonstrate that Pd3P2S8 can be exfoliated down to monolayer, which ultimately will allow the possible control of the localized states in this two-dimensional kagome lattice using the electric field gating.

Flat-band exciton in two-dimensional Kagomé quantum wire systems

2004 ◽  
Vol 69 (8) ◽  
Author(s):  
Hiroyuki Ishii ◽  
Takashi Nakayama ◽  
Jun-ichi Inoue
Keyword(s):  
Quantum Wire ◽  
Flat Band ◽  
Two Dimensional

scholarly journals Flat-band dark polaritons in two-dimensional chiral-waveguide quantum electrodynamics

2021 ◽  
Vol 2015 (1) ◽  
pp. 012088
Author(s):  
Y. Marques ◽  
I. A. Shelykh ◽  
I. V. Iorsh
Keyword(s):  
Quantum Dots ◽  
Quantum Electrodynamics ◽  
Semiconductor Quantum Dots ◽  
Flat Band ◽  
Combined Effects ◽  
Strongly Correlated ◽  
Two Dimensional ◽  
One Dimensional ◽  
Flat Bands ◽  
The One

Abstract We consider a two-dimensional extension of the one-dimensional waveguide quantum electrodynamics and investigate the nature of linear excitations in two-dimensional arrays of qubits (particularly, semiconductor quantum dots) coupled to networks of chiral waveguides. We show that the combined effects of chirality and long-range photon mediated qubit-qubit interactions lead to the emergence of the two-dimensional flat bands in the polaritonic spectrum, corresponding to slow strongly correlated light.

scholarly journals Interaction effects and superconductivity signatures in twisted double-bilayer WSe2

2020 ◽  
Vol 5 (9) ◽  
pp. 1309-1316 ◽  
Author(s):  
Liheng An ◽  
Xiangbin Cai ◽  
Ding Pei ◽  
Meizhen Huang ◽  
Zefei Wu ◽  
...  
Keyword(s):  
Interaction Effects ◽  
Bilayer Graphene ◽  
Insulator Transition ◽  
Electron Interaction ◽  
Flat Band ◽  
Two Dimensional ◽  
Twisted Bilayer Graphene ◽  
Interaction Phenomena

Twisted bilayer graphene provides a new two-dimensional platform for studying electron interaction phenomena and flat band properties such as correlated insulator transition, superconductivity and ferromagnetism at certain magic angles.

scholarly journals Realization of flat band with possible nontrivial topology in electronic Kagome lattice

2018 ◽  
Vol 4 (11) ◽  
pp. eaau4511 ◽  
Author(s):  
Zhi Li ◽  
Jincheng Zhuang ◽  
Li Wang ◽  
Haifeng Feng ◽  
Qian Gao ◽  
...  
Keyword(s):  
Quantum Interference ◽  
Edge State ◽  
Dimensional Structure ◽  
Flat Band ◽  
Destructive Interference ◽  
Two Dimensional ◽  
Kagome Lattice ◽  
Experimental Realization ◽  
Kagomé Lattice ◽  
Nontrivial Topology

The energy dispersion of fermions or bosons vanishes in momentum space if destructive quantum interference occurs in a frustrated Kagome lattice with only nearest-neighbor hopping. A discrete flat band (FB) without any dispersion is consequently formed, promising the emergence of fractional quantum Hall states at high temperatures. Here, we report the experimental realization of an FB with possible nontrivial topology in an electronic Kagome lattice on twisted multilayer silicene. Because of the unique low-buckled two-dimensional structure of silicene, a robust electronic Kagome lattice has been successfully induced by moiré patterns after twisting the silicene multilayers. The electrons are localized in the Kagome lattice because of quantum destructive interference, and thus, their kinetic energy is quenched, which gives rise to an FB peak in the density of states. A robust and pronounced one-dimensional edge state has been revealed at the Kagome edge, which resides at higher energy than the FB. Our observations of the FB and the exotic edge state in electronic Kagome lattice open up the possibility that fractional Chern insulators could be realized in two-dimensional materials.

scholarly journals Evidence of two-dimensional flat band at the surface of antiferromagnetic kagome metal FeSn

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Minyong Han ◽  
Hisashi Inoue ◽  
Shiang Fang ◽  
Caolan John ◽  
Linda Ye ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Finite Energy ◽  
Flat Band ◽  
Tunneling Conductance ◽  
Two Dimensional ◽  
Structure Transition ◽  
Spintronic Devices ◽  
Lattice Geometry ◽  
Planar Tunneling ◽  
Type Semiconductor

AbstractThe kagome lattice has long been regarded as a theoretical framework that connects lattice geometry to unusual singularities in electronic structure. Transition metal kagome compounds have been recently identified as a promising material platform to investigate the long-sought electronic flat band. Here we report the signature of a two-dimensional flat band at the surface of antiferromagnetic kagome metal FeSn by means of planar tunneling spectroscopy. Employing a Schottky heterointerface of FeSn and an n-type semiconductor Nb-doped SrTiO3, we observe an anomalous enhancement in tunneling conductance within a finite energy range of FeSn. Our first-principles calculations show this is consistent with a spin-polarized flat band localized at the ferromagnetic kagome layer at the Schottky interface. The spectroscopic capability to characterize the electronic structure of a kagome compound at a thin film heterointerface will provide a unique opportunity to probe flat band induced phenomena in an energy-resolved fashion with simultaneous electrical tuning of its properties. Furthermore, the exotic surface state discussed herein is expected to manifest as peculiar spin-orbit torque signals in heterostructure-based spintronic devices.

MAGNETIC EXCITATION OF ORTHOGONAL DIMER HEISENBERG SPIN SYSTEM FOR SrCu2(BO3)2

2003 ◽  
Vol 17 (28) ◽  
pp. 5047-5051
Author(s):  
S. MIYAHARA ◽  
K. TOTSUKA ◽  
K. UEDA
Keyword(s):  
Neutron Scattering ◽  
Bound States ◽  
Inelastic Neutron Scattering ◽  
Perturbation Technique ◽  
Dynamic Structure ◽  
Inelastic Neutron ◽  
Magnetic Behaviour ◽  
Lanczos Method ◽  
Flat Band ◽  
Two Dimensional

SrCu 2( BO 3)2 is a new two-dimensional spin gap system and the magnetic behaviour of this compound is explained well by the two-dimensional orthogonal dimer Heisenberg model. Recently several excitations have been observed by inelastic neutron scattering and other experiments. We study features of these excitations by Lanczos method and perturbation technique. A triplet excitation has an almost localised nature. This localised character is observed as an almost flat band in neutron scattering. On the other hand, bound states of two triplet excitations, which have dispersive character, are stable in contrast to ordinary magnetic systems. We calculate the dynamic structure factor by a Lanczos method in finite systems and compare our results with experiments.

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