Phase separation in superconducting and antiferromagnetic Rb0.8Fe1.6Se2 probed by Mössbauer spectroscopy

Vadim Ksenofontov; Gerhard Wortmann; Sergey A. Medvedev; Vladimir Tsurkan; Joachim Deisenhofer; Alois Loidl; Claudia Felser

doi:10.1103/PhysRevB.84.180508

Phase separation in superconducting and antiferromagnetic Rb0.8Fe1.6Se2 probed by Mössbauer spectroscopy

Vadim Ksenofontov, Gerhard Wortmann, Sergey A. Medvedev, Vladimir Tsurkan, Joachim Deisenhofer, Alois Loidl, Claudia Felser

DOI 10.1103/PhysRevB.84.180508 · Physical Review B

T1

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Abstract

57Fe-Mössbauer studies of superconducting Rb0.8Fe1.6Se2.0 with TC = 32.4 K were performed on single-crystalline and polycrystalline samples in the temperature range 4.2–295 K. They reveal the presence of 88% magnetic and 12% nonmagnetic Fe2+ species with the same polarization dependence of their hyperfine spectra. The magnetic species are attributed to the 16i sites of the 5×5×1 superstructure and the nonmagnetic Fe species to a nanosized phase observed in recent structural studies of superconducting KxFe2−ySe2 systems rather than to the vacant 4d sites in the 5×5×1 superstructure. The 57Fe spectrum of a single-crystalline sample in an external field of 50 kOe applied parallel to the crystallographic c axis confirms the antiferromagnetic order between the fourfold ferromagnetic Fe(16i) supermoments and the absence of a magnetic moment at the Fe sites in the minority phase. A discussion of all spectral information and comparison with superconducting FeSe provides convincing evidence that the nanoscale phase separation is monitored by Mössbauer spectroscopy in Rb0.8Fe1.6Se2.0.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Rb0.8Fe1.6Se2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	32.4	Pressure not reported	unknown
Rb0.8Fe1.6Se2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	32.4	Pressure not reported	unknown
Rb0.8Fe1.6Se2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	32.4	Pressure not reported	unknown
Rb0.8Fe1.6Se2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	32.4	Pressure not reported	unknown
FeSe Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	8.5	Pressure not reported	unknown
FeSe Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	36.7	9 GPa	unknown