Spin spirals in FeAs and FeSb studied by Mössbauer spectroscopy
K. Komędera1, A. K. Jasek1, A. Błachowski1, K. Ruebenbauer1,
Z. Bukowski2, A. Krztoń-Maziopa3
1Mössbauer
Spectroscopy Division, Institute of Physics, Pedagogical University, Kraków, Poland
2Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wrocław, Poland
3Faculty of Chemistry, Warsaw University of Technology, Warsaw, Poland
Introduction and Experimental
Discovery of the iron-based superconductors containing iron-pnictogen layers makes
investigation of the iron pnictide compounds quite important.
Iron mono-pnictides are particularly interesting as they exhibit very complex spin ordering
as found e. g. for FeAs by using polarized neutron scattering method [1]. The complex spin
structure is due to competition between metallic and covalent bonds.
Iron pnictides FeAs and FeSb were investigated by means of
spectroscopy versus temperature.
57Fe
Mössbauer
Orthorhombic unit cell of FeAs
57Fe
Mössbauer spectra of FeAs
57Fe
Hexagonal unit cell of FeSb
Mössbauer spectra of FeSb
FeAs
FeSb
Average hyperfine magnetic fields vs. temperature for FeAs [2] and FeSb [3]
FeAs
FeSb
Results and Conclusions
1) The antiferromagnetic ordering temperature was found as 69 K for FeAs
and 232 K for FeSb.
2) The magnetic order leads to the incommensurate spin spirals propagating
through the iron atoms in the direction of the c-axis with a complex pattern of
the hyperfine magnetic fields distributed within a-b plane. Spiral symmetry
corresponds approximately to the symmetry of the electron distribution within
wave functions described by the angular momenta up to two, i.e. up to d
electrons responsible for the itinerant magnetic order.
Magnetic spiral structure
in FeAs [1]
3) Spin spirals are very similar in FeAs and FeSb despite different crystal
symmetry, i.e. orthorhombic for FeAs and hexagonal for FeSb. The possible
reason of this similarity is the octahedral coordination of iron by pnictogen.
Magnetic hyperfine field projection on a-b plane
for spirals propagating along c-axis for FeAs [2] and FeSb [3].
Acknowledgments
This work was supported by the National Science Center of Poland, Grant DEC-2011/03/B/ST3/00446.
References
[1] E.E. Rodriguez et al., Phys. Rev. B 83, 134438 (2011)
[2] A.Błachowski, K.Ruebenbauer, J.Żukrowski, Z.Bukowski, J. Alloys Comp. 582, 167 (2014)
[3] K.Komędera, A.K.Jasek, A.Błachowski, K.Ruebenbauer, A.Krztoń-Maziopa, arXiv:1406.7767 (2014)