Seminars Archive

Femtosecond all-optical relaxation dynamics in iron based pnictides

Abstract
The richness of the iron-based-pnictides phase diagram is reflected also in the transient optical response. Systematic investigations [1-10] of the photo excited quasi-particle relaxation in electron doped 1111 and 122 iron-based pnictides by all-optical methods revealed information regarding the electron phonon coupling,[3, 5] charge gap in the spin-density wave (SDW) state,[3, 5, 6, 8, 9] gaps in the superconducting state[1, 2, 3, 4] and nematic fluctuations in the normal state.[5, 7] Another interesting aspect of the iron-based-pnictides is the presence of rare earth ions in the crystal structure enabling study of a coexistence of the ferromagnetic order of the rare-earth f-orbital spins in EuFe2(As,P)2 and Eu(Fe,Co)2As2 with the superconducting order of the Fe-d-bands carriers. [10] I will briefly review the all-optical relaxation dynamics results in various parts of the phase diagram with emphasis on our recent results concerning the antiferromagnetic (SDW) state[9] and the rare-earth f-orbital spin dynamics in Eu based 122 compounds.[10] 1. T. Mertelj et al., Phys. Rev. Lett. 102, 117002 (2009). 2. E. E. M. Chia et al., Phys. Rev. Lett. 104, 27003 (2010). 3. L. Stojchevska et al., Phys.Rev. B 82, 012505 (2010). 4. D. H. Torchinsky et al., Phys.Rev. B 84, 104518 (2011). 5. L. Stojchevska et al., Phys.Rev. B 86, 024519 (2012). 6. K. W. Kim et al., Nature Mat. 11, 497 (2012). 7. A. Patz et al., Nat. Comm.5, 3229 (2013). 8. T. Mertelj et al., Phys.Rev. B 87, 174525 (2013). 9. A. Pogrebna et al., Phys.Rev. B 89, 165131 (2014). 10. A. Pogrebna et al., Sci. Rep. 5, 7754 (2015).