Optoelectronic devices, plasmonics, and photonics with topological insulators

Politano, Antonio; Viti, Leonardo; Vitiello, Miriam S.

doi:10.1063/1.4977782

Cited by 116 publications

(74 citation statements)

References 145 publications

(220 reference statements)

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“…Strong spin-orbit coupling plays the role of a very high effective magnetic field, which protects the long-lived spin excitation. Such a robust collective spin mode may have potential applications in spintronics [55,56], magnonics [57][58][59], optoelectronics [60] and quantum computing [61][62][63]. Moreover, the present results demonstrate an efficient way of probing the dynamical response of Dirac fermions and their collective modes through optical measurement.…”

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confidence: 69%

Chiral Spin Mode on the Surface of a Topological Insulator

et al. 2017

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Using polarization-resolved resonant Raman spectroscopy, we explore collective spin excitations of the chiral surface states in a three dimensional topological insulator, Bi2Se3. We observe a sharp peak at 150 meV in the pseudovector A2 symmetry channel of the Raman spectra. By comparing the data with calculations, we identify this peak as the transverse collective spin mode of surface Dirac fermions. This mode, unlike a Dirac plasmon or a surface plasmon in the charge sector of excitations, is analogous to a spin wave in a partially polarized Fermi liquid, with spin-orbit coupling playing the role of an effective magnetic field.Magnets and partially spin-polarized Fermi liquids support collective spin excitations (spin waves), in which all electron spins respond coherently to external fields, and the "glue" that locks the phases of precessing spins is provided by the exchange interaction. In nonmagnetic materials where inversion symmetry is broken but time-reversal invariance remains intact, strong spin-orbit coupling (SOC) may play the role of an effective magnetic field, which locks electron spins and momenta into textures. This phenomenon is encountered in threedimensional (3D) topological insulators (TIs), which harbor topologically protected surface states [1][2][3][4][5]. These states have been a focus of intense studies, both from the fundamental point-of-view [6][7][8][9][10][11][12] and for potential applications in spintronics devices [13][14][15][16][17][18][19][20]. However, the many-body interactions leading to collective effects in TIs remain largely unexplored. An essential aspect of this physics is an interplay between the Coulomb interaction and SOC, which is expected to give rise to a new type of collective spin excitations -chiral spin waves [21][22][23][24][25][26]. In the long wavelength (q = 0) limit, these modes are completely decoupled from the charge channel and thus distinct from spin-plasmons [27,28], Dirac plasmons [29,30], and surface plasmons in TIs [30,31].In this Letter, we employ polarization-resolved resonant Raman spectroscopy, a technique of choice for probing the collective charge [32,33], spin [34][35][36][37] and orbital excitations [38], to study collective spin excitations of the chiral surface states in Bi 2 Se 3 . To enhance the signal from the surface states, we tune the energy of incoming photons in resonance with a transition between two sets of chiral surface states: near the Fermi energy and about 1.8 eV above it [ Fig. 1(a)] [39]. We observe a long-lived excitation at 150 meV in the pseudovector symmetry channel of the Raman spectra, which is most pronounced at low temperatures but persists up to room temperature. By comparing the data with calculations, we identify this excitation as the transverse collective chiral spin mode supported by spin-polarized surface Dirac fermions. Such collective modes -first predicted for nontopological systems [21][22][23][24][25][26]36] but hitherto unobserved -are "peeled off" from the continuum of particle-hole excitations by t...

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confidence: 69%

Chiral Spin Mode on the Surface of a Topological Insulator

et al. 2017

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“…Despite great interest from the scientific community, the huge potential of TIs for technological applications has been just started to be exploited [12]. Recent works report superb performance in TI-based nanodevices [13], also thanks to the progress in the control of single-crystal quality during the TI growth process.…”

Section: Opinionmentioning

confidence: 99%

“…Moreover, electron spin and momentum in topologically protected states are locked, thus enabling (i) the control of electron flow and (ii) the reduction of low-frequency noise in TI-based electronic devices [11]. As a matter of fact, the suppression of the backscattering of spin-polarized charge carriers of surface states, with the subsequent suppression of the fluctuation of mobility of surface-state charge carriers, could reduce electronic noise, so as to lower the detection limits of sensors below those already reported [11].Despite great interest from the scientific community, the huge potential of TIs for technological applications has been just started to be exploited [12]. Recent works report superb performance in TI-based nanodevices [13], also thanks to the progress in the control of single-crystal quality during the TI growth process.…”

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confidence: 99%

On the Prospect of Bioelectronics and Biosensors with the Novel Topological Phases of Matter

Politano¹

2017

IJBSBE

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Herein, the application capabilities of novel topological phases of matter in the field of bioelectronics and biosensors are assessed. Topological insulators could enable a novel generation of biosensors, exploiting the reduction of the low-frequency noise arising from the suppressed backscattering. Case-study examples of biosensors based on bismuth chalcogenides are discussed.Keywords: Topological insulators; Biosensors; Bioelectronics; Low-frequency noise OpinionBiosensors are devices of great importance for medical diagnostics, therapy monitoring, environmental science, biotechnology etc. The recent achievements in this fields are based on research on (i) materials and (ii) optimization of processes. By adopting standard solutions, further noteworthy advancement is unfeasible. Conversely, unexplored materials could provide interesting perspectives. The isolation of graphene in 2004 has paved the way for disruptive technologies based on twodimensional materials [1,2]. However, the absence of a band gap in graphene [3] impedes the achievement of a good ON/OFF ratio in nanodevices [4]. Following graphene, other two-dimensional van der Waals semiconductors, combining finite band gaps [5,6] and flexibility [7,8] are emerging in recent years as the most promising materials for nanoelectronics [4,9]. Topological insulators (TIs) are a class of innovative materials, whose physical properties have enormous potential for technological applications [10].TIs represent unique phases of matter with semiconducting bulk and conducting edge or surface states, immune to small perturbations, such as backscattering due to disorder. This stems from their peculiar band structure, which provides topological protection. Moreover, electron spin and momentum in topologically protected states are locked, thus enabling (i) the control of electron flow and (ii) the reduction of low-frequency noise in TI-based electronic devices [11]. As a matter of fact, the suppression of the backscattering of spin-polarized charge carriers of surface states, with the subsequent suppression of the fluctuation of mobility of surface-state charge carriers, could reduce electronic noise, so as to lower the detection limits of sensors below those already reported [11].Despite great interest from the scientific community, the huge potential of TIs for technological applications has been just started to be exploited [12]. Recent works report superb performance in TI-based nanodevices [13], also thanks to the progress in the control of single-crystal quality during the TI growth process. Among TIs, layered bismuth chalcogenides have attracted much attention since they can be easily grown by Bridgman-Stockbarger method and, moreover, since they show TI properties at room temperature [13].

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“…The success of flexible electronics was greatly enabled by innovations in layered semiconductors and novel fabrication techniques [9][10][11][12][13][14][15][16]. Consequently, integrating flexible UWB and MIMO antennas with such devices is ultimately needed for advanced wireless connectivity.…”

Section: Introductionmentioning

confidence: 99%

An Uwb Antenna Array for Flexible Iot Wireless Systems

Raad¹

2018

PIER

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Abstract-In this paper a flexible compact antenna array operating in the 3.213 GHz which covers the standard UltraWide Band (UWB) frequency range is presented. The design is aimed at integration within Multiple Input Multiple Output (MIMO) based flexible electronics for Internet of Things (IoT) applications. The proposed antenna is printed on a single side of a 50.8 µm Kapton Polyimide substrate and consists of two half-elliptical shaped radiating elements fed by two Coplanar Waveguide (CPW) structures. The simulated and measured results show that the proposed antenna array achieves a broad impedance bandwidth with reasonable isolation performance (S 12 < −23 dB) across the operating bandwidth. Furthermore, the proposed antenna exhibits a low susceptibility to performance degradation caused by the effect of bending. The system's isolation performance along with its flexible and thin profile suggests that the proposed antenna is suitable for integration within flexible Internet of Things (IoT) wireless systems.

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Optoelectronic devices, plasmonics, and photonics with topological insulators

Cited by 116 publications

References 145 publications

Chiral Spin Mode on the Surface of a Topological Insulator

Chiral Spin Mode on the Surface of a Topological Insulator

On the Prospect of Bioelectronics and Biosensors with the Novel Topological Phases of Matter

An Uwb Antenna Array for Flexible Iot Wireless Systems

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