Magnetism of BaFe2Se3 studied by Mössbauer spectroscopy

Abstract

The compound BaFe 2 Se 3 (Pnma) has been synthesized in the form of single crystals with the average composition Ba 0.992 Fe 1.998 Se 3 . The Mössbauer spectroscopy used for investigation of the valence states of Fe in this compound at temperature ranging from 4.2 K till room temperature revealed the occurrence of mixed-valence state for iron. The spectrum is characterized by sharply defined electric quadrupole doublet above magnetic ordering at about 250 K. For the magnetically ordered state one sees four iron sites at least and each of them is described by separate axially symmetric electric field gradient tensor with the principal component making some angle with the hyperfine magnetic field. They form two groups occurring in equal abundances. It is likely that each group belongs to separate spin ladder with various tilts of the FeSe 4 tetrahedral units along the ladder. Two impurity phases are found, i.e., superconducting FeSe and some other unidentified iron-bearing phase being magnetically disordered above 80 K. Powder form of BaFe 2 Se 3 is unstable in contact with the air and decomposes slowly to this unidentified phase exhibiting almost the same quadrupole doublet as BaFe 2 Se 3 above magnetic transition temperature.2

Pressure-induced collapse of large-moment magnetic order and localized-to-itinerant electronic transition in the host-guest compound [Cs6Cl][FAdler1, Medvedev2, Valldor3 et al. 2020Phys. Rev. B2010View full textAdd to dashboardCite

“…The shape of the Mössbauer spectra indicates that the magnetic state may correspond to a spiral spin arrangement. The magnetic hyperfine fields are in the range 20-27 T, similar to other iron chalcogenides with insulating ground states [14,27] and quite large magnetic moments >2 μ B . The resistivity data show that with increasing pressure the electronic system becomes more itinerant, which is the origin for the collapse of the complex, large-moment magnetic state in the pressure range between about 5 and 094433-6 .…”

“…The actual distribution of B hf and QS' values is probably even more complex and in the case of an incommensurate spin structure it is expected to be rather quasicontinuous [30]. The B hf values are in the range between about 20 and 27 T, which is comparable to B hf values in BaFe 2 Se 3 [27]. For the latter a magnetic moment of 2.8 μ B was found from neutron diffraction studies [19].…”

“…The shape of the spectrum indicates a nontrivial spin arrangement. Complex hyperfine patterns were also found in the Mössbauer spectra of the magnetic phases of other iron chalcogenides, for instance for the block-type magnetic structure in BaFe 2 Se 3 [26,27] or for the incommensurate collinear spin-density wave Se 26 ] suggests that a spiral spin structure may be formed (cf. the shape of the spectra of the spiral magnet Sr 2 FeO 4 [29]), which leads to anisotropic contributions to the hyperfine field and to differing orientations between the hyperfine field and the electric field gradient due to the spin rotation of the magnetic moments within the spin spiral.…”

The synthesis and magnetic properties of BaFe2Se3 single crystals

“…On the other hand, the changes of the valence state of iron might also lead to the changes of the average electronic spin of iron sites. 43 In order to verify the supposition, the valence state of iron ion was determined by XPS analysis. Fig.…”

First-principles study of magnetic properties in Fe-ladder compoundBaFe2S3

“…[5][6][7] In particular, the block magnetism of BaFe 2 Se 3 has attracted increasing attention as the novel magnetic structure among iron-based materials and has been intensively studied both theoretically [8][9][10][11][12][13] and experimentally. 5,[14][15][16][17][18][19][20][21][22] On the other hand, the physical properties of BaFe 2 S 3 are reported only recently in association with the discovery of the high-T c superconducting transition. …”