scholarly journals Topological insulator metamaterial with giant circular photogalvanic effect

2021 ◽  
Vol 7 (14) ◽  
pp. eabe5748
Author(s):  
X. Sun ◽  
G. Adamo ◽  
M. Eginligil ◽  
H. N. S. Krishnamoorthy ◽  
N. I. Zheludev ◽  
...  
Keyword(s):  
Topological Insulator ◽  
Structural Design ◽  
Surface States ◽  
Optical Excitation ◽  
Fold Increase ◽  
Photogalvanic Effect ◽  
Spin Electronics ◽  
Spin Polarized ◽  
Polarized Surface ◽  
Spin Momentum

One of the most notable manifestations of electronic properties of topological insulators is the dependence of the photocurrent direction on the helicity of circularly polarized optical excitation. The helicity-dependent photocurrents, underpinned by spin-momentum locking of surface Dirac electrons, are weak and easily overshadowed by bulk contributions. Here, we show that the chiral response can be enhanced by nanostructuring. The tight confinement of electromagnetic fields in the resonant nanostructure enhances the photoexcitation of spin-polarized surface states of topological insulator Bi1.5Sb0.5Te1.8Se1.2, leading to an 11-fold increase of the circular photogalvanic effect and a previously unobserved photocurrent dichroism (ρcirc = 0.87) at room temperature. The control of spin transport in topological materials by structural design is a previously unrecognized ability of metamaterials that bridges the gap between nanophotonics and spin electronics, providing opportunities for developing polarization-sensitive photodetectors.

scholarly journals Topological insulator based spin valve devices: Evidence for spin polarized transport of spin-momentum-locked topological surface states

2014 ◽  
Vol 191 ◽  
pp. 1-5 ◽  
Author(s):  
Jifa Tian ◽  
Isaac Childres ◽  
Helin Cao ◽  
Tian Shen ◽  
Ireneusz Miotkowski ◽  
...  
Keyword(s):  
Topological Insulator ◽  
Spin Valve ◽  
Surface States ◽  
Spin Polarized ◽  
Topological Surface ◽  
Polarized Transport ◽  
Spin Polarized Transport ◽  
Spin Momentum

Spin-polarized surface states on Fe-deposited Au(111) surface: A theoretical study

2012 ◽  
Vol 606 (11-12) ◽  
pp. 950-955 ◽  
Author(s):  
Madhura Marathe ◽  
Jérôme Lagoute ◽  
Vincent Repain ◽  
Sylvie Rousset ◽  
Shobhana Narasimhan
Keyword(s):  
Theoretical Study ◽  
Surface States ◽  
Spin Polarized ◽  
Polarized Surface

Topological Insulators: Electronic Structure, Material Systems and Applications

2017 ◽  
Vol 26 (03) ◽  
pp. 1740018
Author(s):  
Parijat Sengupta
Keyword(s):  
Quantum Wells ◽  
Topological Insulator ◽  
Topological Insulators ◽  
Tight Binding ◽  
Surface States ◽  
Internal Electric Field ◽  
Linear Dispersion ◽  
Band Theory ◽  
Magnetic Perturbations ◽  
Polarized Surface

Topological insulators are a new class of materials characterized by fully spin-polarized surface states, a linear dispersion, imperviousness to external non-magnetic perturbations, and a helical character arising out of the perpendicular spin-momentum locking. This article answers in a pedagogical way the distinction between a topological and normal insulator, the role of topology in band theory of solids, and the origin of these surface states. Numerical techniques including diagonalization of the TI Hamiltonians are described to quantitatively evaluate the behaviour of topological insulator states. The Hamiltonians based on continuum and tight binding approaches are contrasted. The application of TIs as components of a fast switching environment or channel material for transistors is examined through I-V curves. The potential pitfall of such devices is presented along with techniques that could potentially circumvent the problem. Additionally, it is demonstrated that a strong internal electric field can also induce topological insulator behaviour with wurtzite nitride quantum wells as representative materials.

scholarly journals Spin-polarized surface states close to adatoms onCu(111)

2006 ◽  
Vol 73 (4) ◽  
Author(s):  
B. Lazarovits ◽  
L. Szunyogh ◽  
P. Weinberger
Keyword(s):  
Surface States ◽  
Spin Polarized ◽  
Polarized Surface

Calculation of spin states of photoelectrons emitted from spin-polarized surface states of Bi(111) surfaces with a mirror symmetry

2017 ◽  
Vol 95 (20) ◽  
Author(s):  
Katsuyoshi Kobayashi ◽  
Koichiro Yaji ◽  
Kenta Kuroda ◽  
Fumio Komori
Keyword(s):  
Mirror Symmetry ◽  
Surface States ◽  
Spin States ◽  
Spin Polarized ◽  
Polarized Surface

Spin Polarized Surface States of Cobalt Nanoislands on Cu(111)

2003 ◽  
Author(s):  
L. Diekhöner
Keyword(s):  
Surface States ◽  
Spin Polarized ◽  
Polarized Surface

scholarly journals Persistent optical gating of a topological insulator

2015 ◽  
Vol 1 (9) ◽  
pp. e1500640 ◽  
Author(s):  
Andrew L. Yeats ◽  
Yu Pan ◽  
Anthony Richardella ◽  
Peter J. Mintun ◽  
Nitin Samarth ◽  
...  
Keyword(s):  
Chemical Potential ◽  
Surface States ◽  
Optical Control ◽  
Electronic Systems ◽  
Optical Gating ◽  
Wide Range ◽  
Spin Polarized ◽  
Electrostatic Gating ◽  
Polarized Surface ◽  
Insulating Phase

The spin-polarized surface states of topological insulators (TIs) are attractive for applications in spintronics and quantum computing. A central challenge with these materials is to reliably tune the chemical potential of their electrons with respect to the Dirac point and the bulk bands. We demonstrate persistent, bidirectional optical control of the chemical potential of (Bi,Sb)2Te3thin films grown on SrTiO3. By optically modulating a space-charge layer in the SrTiO3substrates, we induce a persistent field effect in the TI films comparable to electrostatic gating techniques but without additional materials or processing. This enables us to optically pattern arbitrarily shapedp- andn-type regions in a TI, which we subsequently image with scanning photocurrent microscopy. The ability to optically write and erase mesoscopic electronic structures in a TI may aid in the investigation of the unique properties of the topological insulating phase. The gating effect also generalizes to other thin-film materials, suggesting that these phenomena could provide optical control of chemical potential in a wide range of ultrathin electronic systems.

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