Electronic Structure And Relaxation Dynamics In A Superconducting Topological Material

Abstract

Topological superconductors host new states of quantum matter which show a pairing gap in the bulk and gapless surface states providing a platform to realize Majorana fermions. Recently, alkaline-earth metal Sr intercalated Bi 2 Se 3 has been reported to show superconductivity with a T c ∼ 3 K and a large shielding fraction. Here we report systematic normal state electronic structure studies of Sr 0.06 Bi 2 Se 3 (T c ∼ 2.5 K) by performing photoemission spectroscopy. Using angle-resolved photoemission spectroscopy (ARPES), we observe a quantum well confined two-dimensional (2D) state coexisting with a topological surface state in Sr 0.06 Bi 2 Se 3. Furthermore, our time-resolved ARPES reveals the relaxation dynamics showing different decay mechanism between the excited topological surface states and the two-dimensional states. Our experimental observation is understood by considering the intra-band scattering for topological surface states and an additional electron phonon scattering for the 2D states, which is responsible for the superconductivity. Our first-principles calculations agree with the more effective scattering and a shorter lifetime of the 2D states. Our results will be helpful in understanding low temperature superconducting states of these topological materials.

Publication Date

3-3-2016

Publication Title

Scientific Reports

Volume

6

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1038/srep22557

Socpus ID

84960154385 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84960154385

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