• Hosen, M. Mofazzel
• Alidoust, Nasser
• Zhu, Jian-Xin
• Durakiewicz, Tomasz
• Chou, Fangcheng
• Belopolski, Ilya
• Ishida, Yukiaki
• Sankar, Raman
• Shin, Shik
• Xu, Su-Yang
• Hasan, M. Zahid
• Sanchez, Daniel S.

Abstract

<jats:title>Abstract</jats:title><jats:p>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<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub> has been reported to show superconductivity with a T<jats:sub><jats:italic>c</jats:italic></jats:sub> ~ 3 K and a large shielding fraction. Here we report systematic normal state electronic structure studies of Sr<jats:sub>0.06</jats:sub>Bi<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub> (T<jats:sub><jats:italic>c</jats:italic></jats:sub> ~ 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<jats:sub>0.06</jats:sub>Bi<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub>. 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.</jats:p>

Topics

• impedance spectroscopy
• surface
• two-dimensional
• superconductivity
• superconductivity
• angle-resolved photoelectron spectroscopy