Surface plasmon polaritons in topological insulator nano-films and superlattices

Deshko, Yury; Krusin‐Elbaum, L.; Menon, Vinod M.; Khanikaev, Alexander B.; Trevino, Jacob

doi:10.1364/oe.24.007398

Cited by 33 publications

(20 citation statements)

References 30 publications

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“…In plots of both plasmon frequency as a function of wavevector (Figure 3a) and as a function of film thickness (Figure 3b www.advopticalmat.de plasmons and confirming the theory described in refs. [30,32]. In Figure 3a, the 1 µm samples seem to trend away from the theoretical curves.…”

Section: Wwwadvopticalmatdementioning

confidence: 88%

“…[8][9][10][11] Like graphene, it is expected that TSS plasmons will show increased sensitivity www.advopticalmat.de the bulk, 3D carrier density is constant), [15] resulting in an increase of the plasmon frequency. [30,31] and in the Supporting Information. Finally, Equation (2) shows the dispersion relation for coupled 2D Dirac plasmons.…”

Section: Coupled Dirac Plasmons In Topological Insulatorsmentioning

confidence: 99%

“…[29] Here v F is the Fermi velocity, n D the 2D Dirac carrier density, d is the film thickness, and ε T , ε B , ε TI are the permittivities above, below, and inside the TI, respectively; in this case, ε T is 1 and the equations for ε B and ε TI are given in refs. [30,31] and in the Supporting Information. For coupled 2D Dirac plasmons, the plasmon frequency will increase with film thickness but at much slower rate than 2D massive plasmons.…”

Section: Coupled Dirac Plasmons In Topological Insulatorsmentioning

confidence: 99%

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Coupled Dirac Plasmons in Topological Insulators

Ginley

Law

2018

Advanced Optical Materials

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to refractive index changes, making them more efficient sensors than their noble metal counterparts in addition to reaching previously unobtainable wavelengths. [2] Unlike graphene, TSS electrons exhibit spin-momentum locking, in which the momentum of an electron determines its spin direction. The Dirac electrons are thus protected by time reversal symmetry from backscattering into other surface states in the absence of a magnetic perturbation. [12] TI plasmonics could therefore gain an advantage over graphene since the spin-momentum locking in TIs should lead to spin-polarized plasmons with long propagation distances. [5,13,14] In addition, it is straightforward to grow TI films and multilayered heterostructures on a wafer scale using molecular beam epitaxy. [15][16][17] It is important to note that although the TSSs are 2D, standard TI materials are usually 3D with 2D sheets of topologically protected Dirac electrons on each surface. Plasmon excitations in bulk TI materials have been investigated with electron energy loss spectroscopy measurements, and complex behavior attributed to both trivial surface and topological Dirac electrons has been observed. [18][19][20] Since the TI films discussed in this paper are all in the "thin film" limit of qd < 1 (where q is the wavevector of light and d is the thickness of the film), the plasmons on the top and bottom film surfaces will couple electrostatically. This results in an acoustic (dark) and an optical (bright) plasmon mode. There has been some initial work performed in this system on both the acoustic and optical plasmon modes. [21][22][23][24][25][26][27] Previous work by Di Pietro et al. [23] investigated the dependence of plasmon frequency on stripe width in etched TI films; their observations showed the expected W dependence for 2D plasmons. Though their results were consistent with Dirac plasmons, they were unable to completely rule out the possibility that they observed a 2D massive plasmon instead of the desired 2D massless plasmon.The inherently 3D nature of Bi 2 Se 3 allows for the existence of at least two carrier pathways beyond the TSS: bulk doping and a band bending two-dimensional electron gas (2DEG) at the interface of the TI and adjacent material. [28] One way to distinguish Dirac plasmons from coexisting massive bulk plasmons and massive 2DEG plasmons is by mapping how the plasmon frequency depends on film thickness as well as stripe width. Equation (1) shows the dispersion relation for massive bulk plasmons, where ω p is the plasmon frequency, e is the electron charge, n M is the 2D sheet density, ε r is the average permittivity of the surrounding materials, and q is the wavevector of light. For massive bulk plasmons, n M will increase as the film thickness increases (assuming Topological insulators are predicted to house spin-polarized 2D Dirac plasmons. In topological insulator thin films, Dirac plasmons on the top and bottom surfaces are coupled, giving rise to an unusual dispersion relationship. These plasmons are of interest both for fundam...

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Section: Wwwadvopticalmatdementioning

confidence: 88%

Section: Coupled Dirac Plasmons In Topological Insulatorsmentioning

confidence: 99%

Section: Coupled Dirac Plasmons In Topological Insulatorsmentioning

confidence: 99%

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Coupled Dirac Plasmons in Topological Insulators

Ginley

Law

2018

Advanced Optical Materials

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“…Another possibility for the observance of NPR in flake H1 is the e‐SPP scattering mechanism arising due to the metallic surface states of TIs under illumination at low temperature. SPP (in TIs) refers to the collective oscillation of the light and TSS travelling along the metal surface‐air interface . This novel interaction can generate an additional scattering channel which can lead to the observed NPR.…”

Section: Discussionmentioning

confidence: 99%

Topological Insulator Based Dual State Photo‐Switch Originating Through Bulk and Surface Conduction Channels

Bhattacharyya

Gupta

Senguttuvan

et al. 2018

Physica Status Solidi (b)

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Topological insulators are novel electronic materials, where time reversal symmetry protects the spin‐polarized surface states from backscattering. Although, the bulk offers a trivial semiconducting response to incident light, but the metallic surface states exhibit interesting electrical response towards the incident radiation, such as polarization dependent surface photocurrent and topological phase transitions. Here, we study the temperature dependent near‐infrared photoresponse in bismuth selenide (Bi2Se3) nano‐flakes. A very good photo‐sensitivity to near‐infrared 800 nm wavelength is observed for the temperature range 300–2 K. Voltage responsivity at 2 K (1.481 × 1010 VW−1) is estimated to be four‐order greater than at 300 K (2.095 × 106 VW−1) and is comparatively much higher than the previously reported values of voltage responsivity in other materials. Interestingly, we also find the temperature dependent existence of both positive and negative photoresponse in our device. An anomalous photoresponse reversal is observed at 2 K, where resistance of the nano‐flake increases under light illumination. We propose that this phenomenon is due to the topological surface states, which have dominant transport contribution at very low temperatures. These observations establish the fact that topological insulators can be further engineered to develop a dual state photo‐switch, by manipulating the bulk and surface state conduction contribution.

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“…The 2D-FLs of ∼ 10Å width are formed by surfacestate electrons having a linear energy dispersion near the surface Brillouin zone center, and can support surface plasmons at infrared and lower frequencies in a similar manner as graphene [16,18,19,[22][23][24], as have been shown experimentally [25][26][27][28][29]. Plasmons in TI can be tuned by electrostatic gating and present the additional advantage of carrying spin, which is locked with, and perpendicular to, the direction of propagation of the plasmon, and parallel to the surface at which they are excited.…”

Section: Introductionmentioning

confidence: 99%

Controlling surface charge and spin density oscillations by Dirac plasmon interaction in thin topological insulators

et al. 2018

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Thin topological insulator (TI) films support optical and acoustic plasmonic modes characterized by effective net charge or net spin density, respectively. We combine many-body and electromagnetic calculations to study how these modes can be selectively excited at films and nanodisks at infrared and THz frequencies. We first discuss the excitation of propagating plasmons in a thin film by a point dipolar source. We emphasize how changing the distance between the dipolar source and the film allows to control the relative strength of the acoustic and optical plasmons and thus to excite netspin or net-charge waves on demand. The acoustic and optical modes in a nanodisk structure can be efficiently tuned by changing the size of the disk or by applying electrostatic gating. Furthermore, these modes can be confined to regions of dimensions much smaller than the wavelength. The control of the excitation of acoustic and optical modes indicates that thin topological insulators are a promising system to manipulate the spin and charge properties of the plasmonic response, with potential applications in fast, compact and electrically-controlled spintronic devices.

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Surface plasmon polaritons in topological insulator nano-films and superlattices

Cited by 33 publications

References 30 publications

Coupled Dirac Plasmons in Topological Insulators

Coupled Dirac Plasmons in Topological Insulators

Topological Insulator Based Dual State Photo‐Switch Originating Through Bulk and Surface Conduction Channels

Controlling surface charge and spin density oscillations by Dirac plasmon interaction in thin topological insulators

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