Regular Article

Brightened spin-triplet exciton induced by spin-orbit couplings in semiconducting carbon nanotubes

Physics Department, Nanjing Normal University, Nanjing 210023, P.R. China

^a e-mail: 06183@njnu.edu.cn

Received: 13 September 2019
Received in final form: 10 December 2019
Published online: 3 February 2020

Abstract

Firstly, the multi-band semiconductor Bloch equations (MB-SBE) for the quantum optical properties are reformulated in momentum space to investigate the influence of spin-orbit couplings (SOCs) on the linear optical response of semiconducting carbon nanotubes (SCNTs). One remarkable feature in numerical results is that a new low-strength peak appears at the lower-excited energy position than the peak E₁₁. Comparing the data with/without SOCs, obviously, this new lowest-excited peak originates from the brightened spin-triplet exciton E₁₁^T, which has higher binding energy than the spin-singlet exciton E₁₁^S. For eight SCNTs with small radius, further comparison shows that the appearance and strength of this new peak E₁₁^T is dependent on the chiral of SCNTs. For (n, 1) tubes belonging to the family ν = +1 the effect of SOCs on this new brightened peak E₁₁^T is stronger relative to other SCNTs having the approximative strength of SOCs.