Dipolar optical plasmon in thin-film Weyl semimetals

Giri, Debasmita; Mukherjee, Dibya Kanti; Verma, Sankalp; Fertig, H. A.; Kundu, Arijit

doi:10.48550/arxiv.2011.06862

Cited by 4 publications

(4 citation statements)

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“…In more recent years, the advent of van der Waals materials, particularly graphene, has greatly enriched the set of interesting physical possibilities for two-dimensional plasmons [11][12][13][14][15][16] . These include a myriad of applications and phenomena, in areas as diverse as terahertz radiation, biosensing, photodetection, quantum computing and more [17][18][19][20][21][22][23][24][25][26][27][28][29][30] .…”

Section: Introductionmentioning

confidence: 99%

Plasmonic Transverse Dipole Moment in Chiral Fermion Nanowires

Cao¹,

Fertig²,

Brey³

2022

Preprint

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Plasmons are elementary quantum excitations of conducting materials with Fermi surfaces. In two dimensions they may carry a static dipole moment that is transverse to their momentum which is quantum geometric in nature, the quantum geometric dipole (QGD). We show that this property is also realized for such materials confined in nanowire geometries. Focusing on the gapless, intrasubband plasmon excitations, we compute the transverse dipole moment Dx of the modes for a variety of situations. We find that single chiral fermions generically host non-vanishing Dx, even when there is no intrinsic gap in the two-dimensional spectrum, for which the corresponding twodimensional QGD vanishes. In the limit of very wide wires, the transverse dipole moment of the highest velocity plasmon mode matches onto the two-dimensional QGD. Plasmons of multi-valley systems that are time-reversal symmetric have vanishing transverse dipole moment, but can be made to carry non-vanishing values by breaking the valley symmetry, for example via magnetic field. The presence of a non-vanishing transverse dipole moment for nanowire plasmons in principle offers the possibility of continuously controlling their energies and velocities by the application of a static transverse electric field.c n,ky,τ,s ψ τ k,s ( r),brings the interaction to a form which may be written as V =

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Section: Introductionmentioning

confidence: 99%

Plasmonic Transverse Dipole Moment in Chiral Fermion Nanowires

Cao¹,

Fertig²,

Brey³

2022

Preprint

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“…WSMs must have an even number of Weyl cones: at least four for inversion symmetry broken WSM and two for timereversal symmetry broken ones. Previous studies have shown that the bulk dielectric properties such as Friedel oscillations and (magneto-)plasmons in WSMs [2][3][4][5][6] are different from those of graphene [7,8] due to the increased dimensionality. For example, the bulk plasmon's dispersion in WSMs is gapped and parabolic in momentum while it follows a gapless square-root dispersion in graphene.…”

Section: Introductionmentioning

confidence: 99%

Surface plasmonics of Weyl semimetals

2021

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Smooth interfaces of topological systems are known to host massive surface states in addition to the topologically protected chiral one. We show that in Weyl semimetals these massive states, along with the chiral Fermi arc, strongly alter the form of the Fermi-arc plasmon. Most saliently, they yield further collective plasmonic modes that are absent in a conventional interface. The plasmon modes are completely anisotropic as a consequence of the underlying anisotropy in the surface model and expected to have a clear-cut experimental signature, e.g., in electron-energy loss spectroscopy.

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“…Plasmons are one of such collective modes that results from collective charge oscillations of the system [14,15]. The polarization function and plasmon modes have been studied extensively in 2D semimetals with Dirac like dispersion in the context of Graphene [16][17][18][19], surface of three-dimensional (3D) Weyl and Dirac semimetals [20][21][22][23][24][25][26][27][28][29][30], tilted Dirac semimetal [31,32], and the surface of 3D topological insulators [33][34][35][36]. Recently theory of anisotropic plasmon has also been investigated in Ref.…”

Section: Introductionmentioning

confidence: 99%

Plasmon in Nonsymmorphic Dirac semimetals

Giri¹,

Kundu²

2021

Preprint

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We consider the effect of the Coulomb interaction in a nonsymmorphic Dirac semimetal, leading to collective charge oscillation modes (plasmons), focusing on the model originally predicted by Young and Kane [Phys. Rev. Lett. 115, 126803 (2015)]. We model the system in a two-dimensional squarelattice and evaluate the density-density correlation function within the random-phase approximation (RPA) in presence of the Coulomb interaction. The non-interacting band-structure consists of three band-touching points, near which the electronic states follow Dirac equations. Two of these Dirac nodes, at the momentum points X1 and X2 are anisotropic, i.e, disperses with different velocities in different directions, whereas the third Dirac point at M is isotropic. Interestingly we find that, the system of these three Dirac nodes hold a single low-energy plasmon mode, within its particlehole gap, that disperses in isotropic manner, in the case when the nodes at X1 and X2 are related by symmetry. We also show this analytically using a long-wavelength approximation. We discuss effects of perturbations that can give rise to anisotropic plasmon dispersions and comment on possible experimental observation of our prediction.

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Dipolar optical plasmon in thin-film Weyl semimetals

Cited by 4 publications

References 0 publications

Plasmonic Transverse Dipole Moment in Chiral Fermion Nanowires

Plasmonic Transverse Dipole Moment in Chiral Fermion Nanowires

Surface plasmonics of Weyl semimetals

Plasmon in Nonsymmorphic Dirac semimetals

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