Electronic correlation determining correlated plasmons in Sb-doped Bi2Se3

Abstract

Electronic correlation is believed to play an important role in exotic phenome na such as insulator-metal transition, colossal magneto resistance and high temperature superconductivity in correlated electron systems. Recently, it has been shown that electronic correlation may also be responsible for the formation of unconventional plasmons . Herewith, using a combination of angle-dependent spectroscopic ellipsometry, angle re solved photoemission spectroscopy and Hall measurements all as a function of temperature supported by first-principles calculations, the existence of low-loss high-energy correlated plasmons accompanied by spectral weight transfer, a fingerprint of electronic correlation, in topological insulator (Bi 0.8 Sb 0.2 ) 2 Se 3 is revealed. Upon cooling, the density of free charge carriers in the surface states decreases whereas those in the bulk states increase, and that the newly-discovered correlated plasmons are key to explaining this phenomenon. Our result shows the importance of electronic correlation in determining new correlate d plasmons and opens a new path in engineering plasmonic-based topologically-insulating devices. Introduction: The electronic structure of a three-dimensional topological insulator (TI) consists of novel topological surface states originating from the massless Dirac fermions and insula ting bulk states [1-5]. The time reversal symmetry protected surface states are gapless, while the Fermi level lies in-between the gapped bulk band structure, resulting in an insulating bulk and a conducting surface. Topological insulators have attracted a flurry of research activities not only for their fundamental importance, but they are also being proposed for various real life applications, including field effect transistors [6-8], next generation quantum computers [9, 10],

Unravelling strong electronic interlayer and intralayer correlations in a transition metal dichalcogenide

“…These include colossal magnetoresistance (CMR) 4 , 5 , metal–insulator transitions 6 , 7 , and high-energy resonant excitons 8 , 9 , that are manifested through many-body interactions. Recently, strong electronic correlation effects have also been found to drive plasmons that are found in topological insulators such as bismuth selenide (Bi 2 Se 3 ) when they are cooled 10 , 11 . This is due to the suppression of the electronic screening, which enhances long-range and high-energy electron–electron correlations, revealing topological insulators as strongly-correlated materials.…”

High magneto-Seebeck effect at room temperature in Bi1.8Sb0.2Te3-ySey crystal

“…The results indicate that the doping at y is crucial for tuning the magneto-Seebeck coefficient in Bi 1.8 Sb 0.2 Te 3-y Se y , where large magneto-Seebeck effect is observed with the n-type conduction mechanism in contrast to the p-type conductivity observed for the end compounds. 49 In conclusion, a large magneto-Seebeck effect is observed for ntype Bi 1.8 Sb 0.2 Te 1.5 Se 1.5 , which is $20 times higher than the end compounds having p-type conductivity. Magnetoresistance of BSTS (y ¼ 1.5) is reasonable, which relates linearly to the magneto-Seebeck effect at low temperature.…”

The Effect of Increased Methane Flow Rate on Electronic Correlation of Amorphous Silicon Carbon (a-SiC: H)

“…The p-type layer of a-SiC: H were measured at room temperature in the optical energy range 0.6-6.6 eV. From the results of the sample fitting P-1 and P-2 obtained information and parameters of the optical properties of materials, such as refractive index, dielectric constant, the absorption coefficient, thickness and roughness p-type layer of a-SiC: H. Furthermore, from the complex dielectric function <ε1> and <ɛ2> obtained loss-function, as well as optical conductivity <σ1> and from refractive index <n> and extinction coefficient <k> obtained normal incident reflectivity <R> of each sample [20].…”