Temperature-induced change in the Fermi surface topology in the spin density wave phase of Sr(Fe 1 − x Co x ) 2 As 2

Y. Yang (1, 2) , Yann Gallais (1) , F. Rullier-Albenque (3) , M.-A Méasson (1) , M. Cazayous (1) , A. Sacuto (1) , J. Shi (2) , D. Colson (3, 4) , A. Forget (3, 4)

1 MPQ (UMR_7162) - Laboratoire Matériaux et Phénomènes Quantiques
2 Wuhan University of Science and Technology
3 SPEC - UMR3680 - Service de physique de l'état condensé
4 LNO - Laboratoire Nano-Magnétisme et Oxydes

We report electronic Raman scattering measurements of Sr(Fe1−xCox)2As2 single crystals in their magnetic-Spin Density Wave (SDW) phase. The spectra display multiple, polarization-resolved SDW gaps as expected in a band-folding itinerant picture for a multiband system. The temperature dependence of the SDW gaps reveals an unusual evolution of the reconstructed electronic structure with at least one gap being activated only well below the magnetic SDW transition TN. A comparison with temperature dependent Hall measurements allows us to assign this activated behavior to a change in the Fermi surface topology deep in the SDW phase, which we attribute to the disappearance of a hole-like Fermi pocket. Our results highlight the strong sensitivity of the low energy electronic structure to temperature in iron-arsenide superconductors.

Domaines: Physique [physics]

Y. Yang, Yann Gallais, F. Rullier-Albenque, M.-A Méasson, M. Cazayous, et al.. Temperature-induced change in the Fermi surface topology in the spin density wave phase of Sr(Fe 1 − x Co x ) 2 As 2. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2014, 89 (12), pp.125130. ⟨10.1103/PhysRevB.89.125130⟩. ⟨cea-01377158⟩