Electronic and crystalline structure of Co- and Te-Substituted FeSe

International Conference and Exhibition on Mesoscopic & Condensed Matter Physics

June 22-24, 2015 Boston, USA

Israel Perez1, Jos�© E Trinidad-Galindo1, John Mcleod2, Alexander Moewes2, Robert Green2, Raul Escamilla3 and V�­ctor Ort�­z3

1Universidad Aut�³noma de Ciudad Ju�¡rez, Mexico 2Universidad de Saskatchewan, Canada 3Universidad Nacional Aut�³noma de M�©xico, Mexico

Posters-Accepted Abstracts: J Material Sci Eng

Abstract :

Herein we report the results from the study of the electronic and crystalline structure of Fe1- xCoxSe and FeSe1-xTex (x=0-1). For our analysis we used X-ray emission spectroscopy (XES), resonant inelastic X-ray scattering (RIXS), X-ray diffraction (XRD), and density functional theory (DFT). With these tools we determined the crystalline structure of our systems and probe the unoccupied levels (conduction band). The results indicate that under Fe substitution by Co, there is a solubility limit starting at x=0.38 where the hexagonal phase dominates the system. It is assumed that the structural transition suppresses superconductivity even for relatively low Co concentrations (x>0.15). In the case of Se substitution by Te, we confirmed that the tetragonal phase remains for all concentrations although the lattice parameters increase and the lattice distorts. These findings support the view that the tetragonal phase is indispensible for superconductivity in this system. Regarding the electronic properties of both systems, both calculations and measurements suggest that Fe behaves metallic and do not form strong bonds with Se, Co or Te suggesting that the system cannot be regarded as a strongly correlated. Finally, using RIXS, we found that the spin state of our systems fluctuates between S=0 and 2. This is important because the model suggests a correlation between the spin state and the magnetic order.

Biography :

Email: ioperez@conacyt.mx