Investigations of proximity-induced superconductivity in the topological insulator Bi2Te3 by microRaman spectroscopy

Abstract

We used the topological insulator (TI) Bi2Te3 and a high-temperature superconductor (HTSC) hybrid device for investigations of proximity-induced superconductivity (PS) in the TI. Application of the superconductor YBa2Cu3O7-δ (YBCO) enabled us to access higher temperature and energy scales for this phenomenon. The HTSC in the hybrid device exhibits emergence of a pseudogap state for T > Tc that converts into a superconducting state with a reduced gap for T < Tc. The conversion process has been reflected in Raman spectra collected from the TI. Complementary charge transport experiments revealed emergence of the proximity-induced superconducting gap in the TI and the reduced superconducting gap in the HTSC, but no signature of the pseudogap. This allowed us to conclude that Raman spectroscopy reveals formation of the pseudogap state but cannot distinguish the proximity-induced superconducting state in the TI from the superconducting state in the HTSC characterised by the reduced gap. Results of our experiments have shown that Raman spectroscopy is a complementary technique to classic charge transport experiments and is a powerful tool for investigation of the proximity-induced superconductivity in the Bi2Te3.

Nonwoven Polymeric Nanofiber Sheets: Path Forward Toward a New Class of Hybrid Flexible Thermoelectrics

“…[ 49–51 ] But in the low dimension, that is, 2D or 1D, one more strong peak appears in Raman spectra corresponding to mode A 1u which remains Raman inactive in bulk Bi 2 Te 3 . [ 50,52,53 ] From Figure 5, it is clear that wrapped Bi 2 Te 3 on NFs is in low dimension because, in the Raman spectra of CA‐500 and P ‐500, we have observed peaks corresponding to the modes A 1g 1 , E g 2 , A 1u 2 , and A 1g 2 at ≈ 65, 100, 119, 139 cm −1 , respectively, which are in close agreement with the earlier studies. [ 50,54,55 ] The intensity of A 1u 2 mode is higher than that of the in‐plane E g 2 mode and also the shifting of A 1g 2 mode toward higher Raman shift ≈140 cm −1 as compared to bulk Bi 2 Te 3 , where it is observed generally at ≈133 cm −1 [ 50,53,54 ] and thus confirm the nano‐dimensional deposition of Bi 2 Te 3 on NFs in present samples.…”

“…[49][50][51] But in the low dimension, that is, 2D or 1D, one more strong peak appears in Raman spectra corresponding to mode A 1u which remains Raman inactive in bulk Bi 2 Te 3 . [50,52,53] From Figure 5, it is clear that wrapped Bi 2 Te 3 on NFs is in low dimension because, in the Raman spectra of CA-500 and P-500, we have observed peaks corresponding to the modes A 1g…”

Effect of the Post‐Annealing Temperature on the Interfacial Reaction Between a High TC Superconductor and Topological Insulator

“…[ 4 ] These phenomena enable the development of quantum computers, spintronics, and novel optoelectronics. [ 5,6 ] However, only a few studies have reported the “superconducting proximity effect” on the heterojunction between HTS and TI. [ 6 ] Investigating this effect is challenging owing to the complex structure of cuprate oxide based‐HTS, which may limit the formation of abrupt heterojunctions after the deposition of another layer.…”