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Title: In situ Investigation of Magnetism in Metastable Phases of Levitated Fe 83 B 17 During Solidification

Authors:
; ; ; ; ;
Publication Date:
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1409872
Grant/Contract Number:
AC02-07CH11358
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review Applied
Additional Journal Information:
Journal Volume: 8; Journal Issue: 5; Related Information: CHORUS Timestamp: 2017-11-22 10:06:51; Journal ID: ISSN 2331-7019
Publisher:
American Physical Society
Country of Publication:
United States
Language:
English

Citation Formats

Quirinale, D. G., Messina, D., Rustan, G. E., Kreyssig, A., Prozorov, R., and Goldman, A. I. In situ Investigation of Magnetism in Metastable Phases of Levitated Fe 83 B 17 During Solidification. United States: N. p., 2017. Web. doi:10.1103/PhysRevApplied.8.054046.
Quirinale, D. G., Messina, D., Rustan, G. E., Kreyssig, A., Prozorov, R., & Goldman, A. I. In situ Investigation of Magnetism in Metastable Phases of Levitated Fe 83 B 17 During Solidification. United States. doi:10.1103/PhysRevApplied.8.054046.
Quirinale, D. G., Messina, D., Rustan, G. E., Kreyssig, A., Prozorov, R., and Goldman, A. I. Wed . "In situ Investigation of Magnetism in Metastable Phases of Levitated Fe 83 B 17 During Solidification". United States. doi:10.1103/PhysRevApplied.8.054046.
@article{osti_1409872,
title = {In situ Investigation of Magnetism in Metastable Phases of Levitated Fe 83 B 17 During Solidification},
author = {Quirinale, D. G. and Messina, D. and Rustan, G. E. and Kreyssig, A. and Prozorov, R. and Goldman, A. I.},
abstractNote = {},
doi = {10.1103/PhysRevApplied.8.054046},
journal = {Physical Review Applied},
number = 5,
volume = 8,
place = {United States},
year = {Wed Nov 22 00:00:00 EST 2017},
month = {Wed Nov 22 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on November 22, 2018
Publisher's Accepted Manuscript

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  • In situ measurements of structure, density, and magnetization on samples of Fe 83 B 17 using an electrostatic levitation furnace allow us to identify and correlate the magnetic and structural transitions in this system during its complex solidification process. In particular, we identify magnetic ordering in the metastable Fe 23 B 6 / fcc Fe coherently grown structures and primitive tetragonal Fe 3 B metastable phase in addition to characterizing the equilibrium Fe 2 B phase. Our measurements demonstrate that the incorporation of a tunnel-diode oscillator circuit within an electrostatic levitation furnace enables investigations of the physical properties of high-temperaturemore » metastable structures.« less
  • We report comprehensive 77 Se NMR measurements on a single crystalline sample of the recently discovered FeSe-based high-temperature superconductor K x Fe 2 - y Se 2 ( T c = 33 K) in a broad temperature range up to 290 K. Despite deviations from the stoichiometric KFe 2 Se 2 composition, we observed 77 Se NMR line shapes as narrow as 4.5 kHz under a magnetic field applied along the crystal c axis, and found no evidence for co-existence of magnetic order with superconductivity. On the other hand, the 77 Se NMR line shape splits into two peaks withmore » equal intensities at all temperatures when we apply the magnetic field along the ab plane. This suggests that K vacancies may have a superstructure and that the local symmetry of the Se sites is lower than the tetragonal fourfold symmetry of the average structure. This effect might be a prerequisite for stabilizing the s ± symmetry of superconductivity in the absence of the hole bands at the Brillouin zone center. From the increase of NMR linewidth below T c induced by the Abrikosov lattice of superconducting vortices, we estimate the in-plane penetration depth λ ab ~ 290 nm and the carrier concentration n e ~ 1 × 10 + 21 cm - 3 . Our Knight shift 77 K data indicate that the uniform spin susceptibility decreases progressively with temperature, in analogy with the case of FeSe ( T c ~ 9 K) as well as other FeAs high- T c systems. The strong suppression of 77 K observed immediately below T c for all crystal orientations is consistent with a singlet pairing of Cooper pairs. We do not however observe the Hebel-Slichter coherence peak of the nuclear spin-lattice relaxation rate 1 / T 1 immediately below T c , expected for conventional BCS s-wave superconductors. In contrast with the case of FeSe, we do not observe evidence for an enhancement of low-frequency antiferromagnetic spin fluctuations near T c in 1 / T 1 T . Instead, 1 / T 1 T exhibits qualitatively the same behavior as overdoped non-superconducting Ba(Fe 1 - x Co x ) 2 As 2 with x ~ 0 . 14 or greater, where hole bands are missing in the Brillouin zone center. We will discuss the implications of our results on the unknown mechanism of high-temperature superconductivity in FeSe and FeAs systems.« less
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