Abstract:
The FeTe parent compound for iron-superconductor chalcogenides
was studied applying Mossbauer spectroscopy accompanied
by ab initio calculations of electric field gradients
at the iron nuclei. Room-temperature (RT) Mossbauer
spectra of single crystals have shown asymmetric doublet
structure commonly ascribed to contributions of overstoichiometric
iron or impurity phases. Low-temperature
Mossbauer spectra of the magnetically ordered compound
could be well described by four hyperfine-split sextets, although
no other foreign phases different from Fe1.05Te were
detected by XRD and microanalysis within the sensitivity
limits of the equipment. Density functional ab initio calculations
have shown that over-stoichiometric iron atoms significantly
affect electron charge and spin density up to the
second coordination sphere of the iron sub-lattice, and, as a
result, four non-equivalent groups of iron atoms are formed
by their local environment. The resulting four-group model
consistently desc
