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Tortora L, Tomassucci G, Pugliese GM, Hacisalihoglu MY, Simonelli L, Marini C, Das G, Ishida S, Iyo A, Eisaki H, Mizokawa T, Saini NL. Anisotropic atomic displacements, local orthorhombicity and anomalous local magnetic moment in Ba 0.6K 0.4Fe 2As 2 superconductor. Phys Chem Chem Phys 2024. [PMID: 39140998 DOI: 10.1039/d4cp02345e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/15/2024]
Abstract
We have investigated the in-plane local structure of the Ba0.6K0.4Fe2As2 superconductor by polarized Fe K-edge extended X-ray absorption fine structure (EXAFS) measurements with temperature. The near neighbor bond distances and their stiffness, measured by polarized EXAFS in two orthogonal directions, are different suggesting in-plane anisotropy of the atomic displacements and local orthorhombicity in the title system. The X-ray absorption near edge structure (XANES) spectra reveal anisotropy of valence electronic structure that changes anomalously below ∼100 K. The local iron magnetic moment, measured by Fe Kβ X-ray emission spectroscopy (XES), increases below the anomalous temperature and shows a decrease in the vicinity of the superconducting transition temperature (Tc ∼ 36 K). The results provide a clear evidence of coupled local lattice, electronic and magnetic degrees of freedom to induce possible nematic fluctuations in an optimally hole doped iron-based superconductor.
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Affiliation(s)
- L Tortora
- Dipartimento di Fisica, Universitá di Roma "La Sapienza" - P. le Aldo Moro 2, 00185 Roma, Italy.
| | - G Tomassucci
- Dipartimento di Fisica, Universitá di Roma "La Sapienza" - P. le Aldo Moro 2, 00185 Roma, Italy.
| | - G M Pugliese
- Dipartimento di Fisica, Universitá di Roma "La Sapienza" - P. le Aldo Moro 2, 00185 Roma, Italy.
| | - M Y Hacisalihoglu
- Dipartimento di Fisica, Universitá di Roma "La Sapienza" - P. le Aldo Moro 2, 00185 Roma, Italy.
| | - L Simonelli
- CELLS - ALBA Synchrotron Radiation Facility, Carrer de la Llum 2-26, 08290, Cerdanyola del Valles, Barcelona, Spain
| | - C Marini
- CELLS - ALBA Synchrotron Radiation Facility, Carrer de la Llum 2-26, 08290, Cerdanyola del Valles, Barcelona, Spain
| | - G Das
- Elettra Sincrotrone Trieste, Strada Statale 14, Km 163.5, Basovizza, 34149 Trieste, Italy
| | - S Ishida
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan
| | - A Iyo
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan
| | - H Eisaki
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan
| | - T Mizokawa
- Department of Applied Physics, Waseda University, Tokyo 169-8555, Japan
| | - N L Saini
- Dipartimento di Fisica, Universitá di Roma "La Sapienza" - P. le Aldo Moro 2, 00185 Roma, Italy.
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Manivannan N, Subirana MA, Boada R, Marini C, Llugany M, Valiente M, Simonelli L. Mercury speciation in selenium enriched wheat plants hydroponically exposed to mercury pollution. Sci Rep 2023; 13:21132. [PMID: 38036518 PMCID: PMC10689832 DOI: 10.1038/s41598-023-46056-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 10/27/2023] [Indexed: 12/02/2023] Open
Abstract
Mercury (Hg) pollution in agricultural soils and its potential pathway to the human food chain can pose a serious health concern. Understanding the pathway of Hg in plants and how the speciation may change upon interaction with other elements used for biofortification can be critical to assess the real implications for the final plant-based product. In that respect, selenium (Se) biofortification of crops grown in Se-poor soil regions is becoming a common practice to overcome Se deficient diets. Therefore, it is important to assess the interplay between these two elements since Se may form complexes with Hg reducing its bioavailability and toxicity. In this work, the speciation of Hg in wheat plants grown hydroponically under the presence of Hg (HgCl2) and biofortified with Se (selenite, selenate, or a 1:1 mixture of both) has been investigated by X-ray absorption spectroscopy at the Hg L3-edge. The main Hg species found in wheat grains was the highly toxic methylmercury. It was found that the Se-biofortification of wheat did not prevent, in general, the Hg translocation to grains. Only the 1:1 mixture treatment seemed to have an effect in reducing the levels of Hg and the presence of methylmercury in grains.
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Affiliation(s)
- Nithyapriya Manivannan
- ALBA Synchrotron, Carrer de la llum 2-26, Cerdanyola del Vallès, 08290, Barcelona, Spain
- GTS-UAB Research Group, Department of Chemistry, Faculty of Science, Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain
| | - Maria Angels Subirana
- GTS-UAB Research Group, Department of Chemistry, Faculty of Science, Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain
| | - Roberto Boada
- ALBA Synchrotron, Carrer de la llum 2-26, Cerdanyola del Vallès, 08290, Barcelona, Spain
- GTS-UAB Research Group, Department of Chemistry, Faculty of Science, Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain
| | - Carlo Marini
- ALBA Synchrotron, Carrer de la llum 2-26, Cerdanyola del Vallès, 08290, Barcelona, Spain
| | - Mercè Llugany
- Plant Physiology Group (BABVE), Faculty of Biosciences, Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain
| | - Manuel Valiente
- GTS-UAB Research Group, Department of Chemistry, Faculty of Science, Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain
| | - Laura Simonelli
- ALBA Synchrotron, Carrer de la llum 2-26, Cerdanyola del Vallès, 08290, Barcelona, Spain.
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Tomassucci G, Tortora L, Pugliese GM, Stramaglia F, Simonelli L, Marini C, Terashima K, Wakita T, Ayukawa S, Yokoya T, Kudo K, Nohara M, Mizokawa T, Saini NL. Temperature dependent local inhomogeneity and magnetic moments of (Li 1-xFe x)OHFeSe superconductors. Phys Chem Chem Phys 2023; 25:6684-6692. [PMID: 36806473 DOI: 10.1039/d3cp00004d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We have combined the extended X-ray absorption fine structure (EXAFS) and X-ray emission spectroscopy (XES) to investigate the local structure and the local iron magnetic moments of (Li1-xFex)OHFeSe (x∼0.2) superconductors. The local structure, studied by Fe K-edge EXAFS measurements, is found to be inhomogeneous that is characterized by different Fe-Se bond lengths. The inhomogeneous phase exhibits a peculiar temperature dependence with lattice anomalies in the local structural parameters at the critical temperature Tc (36 K) and at the spin density wave (SDW) transition temperature TN (130 K). Fe Kβ XES shows iron to be in a low spin state with the local Fe magnetic moment evolving anomalously as a function of temperature. Apart from a quantitative measurement of the local structure of (Li1-xFex)OHFeSe, providing direct evidence of nanoscale inhomogeneity, the results provide further evidence of the vital role that the coupled electronic, lattice and magnetic degrees of freedom play in the iron-based superconductors.
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Affiliation(s)
- G Tomassucci
- Dipartimento di Fisica, Universitá di Roma "La Sapienza" - P. le Aldo Moro 2, 00185 Roma, Italy.
| | - L Tortora
- Dipartimento di Fisica, Universitá di Roma "La Sapienza" - P. le Aldo Moro 2, 00185 Roma, Italy.
| | - G M Pugliese
- Dipartimento di Fisica, Universitá di Roma "La Sapienza" - P. le Aldo Moro 2, 00185 Roma, Italy.
| | - F Stramaglia
- Dipartimento di Fisica, Universitá di Roma "La Sapienza" - P. le Aldo Moro 2, 00185 Roma, Italy. .,Microscopy and Magnetism Group, Swiss Light Source, Paul Scherrer Institut, Villigen, Switzerland
| | - L Simonelli
- CELLS - ALBA Synchrotron Radiation Facility, Carrer de la Llum 2-26, 08290, Cerdanyola del Valles, Barcelona, Spain
| | - C Marini
- CELLS - ALBA Synchrotron Radiation Facility, Carrer de la Llum 2-26, 08290, Cerdanyola del Valles, Barcelona, Spain
| | - K Terashima
- Research Institute for Interdisciplinary Science (RIIS), Okayama University, Okayama 700-8530, Japan.,National Institute for Materials Science, Sengen 1-2-1, Tsukuba, Ibaraki 305-0047, Japan
| | - T Wakita
- Research Institute for Interdisciplinary Science (RIIS), Okayama University, Okayama 700-8530, Japan
| | - S Ayukawa
- Research Institute for Interdisciplinary Science (RIIS), Okayama University, Okayama 700-8530, Japan
| | - T Yokoya
- Research Institute for Interdisciplinary Science (RIIS), Okayama University, Okayama 700-8530, Japan
| | - K Kudo
- Department of Physics, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - M Nohara
- Department of Quantum Matter, Hiroshima University, Hiroshima 739-8530, Japan
| | - T Mizokawa
- Department of Applied Physics, Waseda University, Tokyo 169-8555, Japan
| | - N L Saini
- Dipartimento di Fisica, Universitá di Roma "La Sapienza" - P. le Aldo Moro 2, 00185 Roma, Italy.
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