Infrared spectroscopic ellipsometry and optical spectroscopy of plasmons in classic 3D topological insulators

Abstract

Narrow bandgap Bi2Se3, Bi2Te3, and Sb2Te3, commonly referred to as classic 3D topological insulators, were studied at room temperature by spectroscopic ellipsometry and optical reflection spectroscopy over the mid-IR–near-infrared photon energy range. Complementarily, Hall measurements were performed. Plasmons in optical loss function and reflection coefficient were identified. The conventional approach based on the high frequency dielectric constant was shown to work well in the description of plasmons in Bi2Se3 and Sb2Te3 and to fail in the case of a similar compound, Bi2Te3. The obtained results are discussed in terms of single- and multivalley approaches to the studied samples with taking the details of the calculated band structure into account.

THERMODYNAMİC PROPERTİES OF THE Bi2Te3 AND Bi4Te5 COMPOUNDS

“…the partial molar Gibbs free energy, enthalpy, and entropy of bismuth in the alloys were calculated (Table 4). (11) the standard thermodynamic functions of the formation of Bi 2 Te 3 and Bi 4 Te 5 were calculated. In relations (8) and (9) Z  G or H. For the thermodynamic calculations, we used the literature data [29] on the standard entropies of elementary bismuth (56.7 ± 0.5 Jmol -1 К -1 ) and tellurium (49.5±0.2 Jmol -1 К -1 ).…”

“…Bismuth tellurides, especially Bi 2 Тe 3 , phases, and composites based on it have long been in the field of view of researchers as valuable thermoelectric materials [1][2][3]. After the discovery of a special quantum state of mattera topological insulator (TI) [4], it was found that Bi2Te3 and many other layered compounds of tetradimite-like structures are TI which are rather promising for their varied applications [5][6][7][8][9][10][11]. In particular, the unique optical properties make them promising for the use in broadband optoelectronics as photodetectors [12][13][14][15].…”

Исследование плазмонного резонанса в Bi-=SUB=-2-=/SUB=-Se-=SUB=-3-=/SUB=- и Sb-=SUB=-2-=/SUB=-Te-=SUB=-3-=/SUB=- методом инфракрасной спектральной эллипсометрии

“…Ранее в литературе было показано, что частоты возбуждения ППР в Bi 2 Se 3 и Sb 2 Te 3 приходятся на ИК область, тем самым исследование Bi 2 Se 3 и Sb 2 Te 3 в качестве плазмонных материалов становится очень перспективным направлением. Плазменная частота зависит от концентрации свободных носителей заряда, эта зависимость описывается известной формулой [7]:…”

“…где ω -частота электромагнитной волны, ε a -диэлектрическая постоянная призмы, c -скорость света и θугол падения волны. Ранее публиковались работы по наблюдению плазмонов в данных соединениях и в других структурах типа тетрадимит [7,9,10], но сведений о ППР и его применении для ИК плазмонных устройств и исследования свойств плазмона в литературе нет. В данной работе это выполнено впервые.…”

FeS–FeGaInS4–FeIn2S4 SYSTEM

“…The above compounds also apply to materials promising for the specified area [9][10][11]. MnBi 2 Te 4 (the first antiferromagnetic topological insulator) MnBi 4 Te 7 and MnBi 6 Te 10 compounds were described in papers [12][13][14][15] publicshed recently.…”