Abstract
Iron selenide (FeSe) was used to investigate magnetic properties by using Mössbauer spectroscopy. The crystalline structure of the sample was found to be tetragonal and hexagonal with a 3c structure. The temperature-dependent magnetic susceptibility curve under 100 Oe confirmed the spin rotation temperature TS = 150 K. Based on the applied field dependent magnetization measurements up to 15 kOe at 295 K, the saturation magnetization and coercivity were found to be 8.03 emu/g and 357.40 Oe, respectively. The spin rotation process of the sample from the dependence temperature ZFC-FC curves occurs at approximately TS. The Mössbauer spectra below the Néel temperature (TN) were fitted with a doublet for the tetragonal phase and three sextets (A, B, and C sites) for the hexagonal phase. The spectrum was fitted to a single line at TN = 500 K. We also observed abrupt changes in Hhf and ΔEQ at the spin rotation temperature. The Fe charge states in the tetragonal and hexagonal phases are found to be ferric and highly covalent ferrous ion (or high-spin ferric), respectively.
Highlights
Iron-based superconductivity is advancing considerably in several areas owing to its optical, electronic, and magnetic properties.1–4 Since the discovery of superconductivity at 26 K in iron arsenide La[O1-xFx]FeAs,5 research on superconductors has generated a garnered significant attention
We have investigated the magnetic characteristics of tetragonal and 3c hexagonal phases present in commercial FeSe compounds based on Mössbauer spectroscopy
At temperatures below TN, the spectra were fitted with a doublet for the tetragonal structure and three sets of six Lorentzian lines for Fe sites corresponding to the A, B, and C sites in the hexagonal structure, as shown in Figs. 3 and 4
Summary
Iron-based superconductivity is advancing considerably in several areas owing to its optical, electronic, and magnetic properties. Since the discovery of superconductivity at 26 K in iron arsenide La[O1-xFx]FeAs, research on superconductors has generated a garnered significant attention. Iron-based superconductivity is advancing considerably in several areas owing to its optical, electronic, and magnetic properties.. Among the iron-based superconductors, FeSe discovered by Hsu et al is a superconducting material that has the simplest crystal structure.. The main barrier in the synthesis of FeSe superconductors is the emergence of a hexagonal phase (δ-FeSe with a NiAs structure or 3c-Fe7Se8) that does not have superconducting properties.. In the case of commercial FeSe compounds, it is difficult to match the precise stoichiometric amounts of Fe and Se; there is a possibility that tetragonal and hexagonal phases exist simultaneously in FeSe. D. Mendoza et al. reported that commercial FeSe contains a main pick of tetragonal and hexagonal structures that can be indexed as the secondary phase Fe7Se8
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