"Spectrally resolved femtosecond reflectivity relaxation dynamics in undoped spin-density wave 122-structure iron-based pnictides"

A. Pogrebna: N. Vujičić, T. Mertelj, T. Borzda, G. Cao, Z. A. Xu, J.-H. Chu, I. R. Fisher, and D. Mihailovic; Phys. Rev. B 89, 04/24/2014.

Additional Authors: N. Vujičić, T. Mertelj, T. Borzda, G. Cao, Z. A. Xu, J.-H. Chu, I. R. Fisher, and D. Mihailovic

Abstract:

We systematically investigate temperature- and spectrally dependent optical reflectivity dynamics in A As2Fe2, (A=Ba , Sr, and Eu), iron-based superconductors parent spin-density wave (SDW) compounds. Two different relaxation processes are identified. The behavior of the slower process, which is strongly sensitive to the magnetostructural transition, is analyzed in the framework of the relaxation-bottleneck model involving magnons. The results are compared to recent time-resolved angular photoemission results (TR-ARPES) and possible alternative assignment of the slower relaxation to the magnetostructural order parameter relaxation is discussed.