Structural and magnetic phase transitions in the ternary iron arsenides SrFe2As2 and EuFe2As2

Abstract

The structural and magnetic phase transitions of the ternary iron arsenides SrFe2As2 and EuFe2As2 were studied by temperature-dependent x-ray powder diffraction and 57-Fe Moessbauer spectroscopy. Both compounds crystallize in the tetragonal ThCr2Si2-type structure at room temperature and exhibit displacive structural transitions at 203 K (SrFe2As2) or 190 K (EuFe2As2) to orthorhombic lattice symmetry in agreement with the group-subgroup relationship between I4/mmm and Fmmm. 57-Fe Moessbauer spectroscopy experiments with SrFe2 As2 show full hyperfine field splitting below the phase transition temperature (8.91(1) T at 4.2 K). Order parameters were extracted from detailed measurements of the lattice parameters and fitted to a simple power law. We find a relation between the critical exponents and the transition temperatures for AFe2As2 compounds, which shows that the transition of BaFe2As2 is indeed more continuous than the transition of SrFe2As2 but it remains second order even in the latter case.

11 pages, 6 figures, text revised, one figure amended

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Cited by in corpus (14)

• Lattice and magnetic instabilities in CaFe2As2: A single crystal neutron diffraction study
• Possible re-entrant superconductivity in EuFe2As2 under pressure
• Transport and anisotropy in single-crystalline SrFe${}_2$As${}_2$ and $A_{0.6}$K${}_{0.4}$Fe${}_2$As${}_2$ ($A$ = Sr, Ba) superconductors
• Strong coupling between magnetic and structural order parameters in SrFe2As2
• Competition of magnetism and superconductivity in underdoped (Ba1-xKx)Fe2As2
• Effects of the magnetic orderings on the dynamical conductivity: optical investigations of EuFe${}_2$As${}_2$ single crystals
• Synthesis, crystal structure and spin-density-wave anomaly of the iron arsenide-fluoride SrFeAsF
• Feshbach resonances and mesoscopic phase separation near a quantum critical point in multiband FeAs-based superconductors
• Phonon anomalies in pure and underdoped R{1-x}K{x}Fe{2}As{2} (R = Ba, Sr) investigated by Raman light scattering
• Water-induced superconductivity in SrFe2As2
• Superconductivity induced by ruthenium substitution in an iron arsenide: investigation of SrFe2-xRuxAs2 (0 <= x <= 2)
• Atomically-flat, chemically-stable, superconducting epitaxial thin film of iron-based superconductor, cobalt-doped BaFe${}_2$As${}_2$
• Electronic structure of BaCu${}_2$As${}_2$ and SrCu${}_2$As${}_2$: sp-band metals
• Magnetic and lattice coupling in single-crystal SrFe${}_2$As${}_2$: A neutron scattering study