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Yoshiaki Hara

Bio: Yoshiaki Hara is an academic researcher from University of Oxford. The author has contributed to research in topics: Materials science & Condensed matter physics. The author has an hindex of 2, co-authored 2 publications receiving 629 citations.

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Journal ArticleDOI
TL;DR: In this paper, the composition of the spacer layers present in iron-based superconductors is altered to increase the temperature below which they superconduct, and intercalating FeSe with molecular spacer layer is also shown to enhance the superconducting transition temperature.
Abstract: Altering the composition of the spacer layers present in iron-based superconductors is one strategy for increasing the temperature below which they superconduct. Now, intercalating FeSe with molecular spacer layers is also shown to enhance the superconducting transition temperature.

365 citations

Journal ArticleDOI
TL;DR: The synthesis of Li(x)( NH(2))(y)(NH(3))(1-y)Fe(2)Se(2), with lithium ions, lithium amide and ammonia acting as the spacer layer between FeSe layers, which exhibits superconductivity at 43(1) K, higher than in any FeSe-derived compound reported so far.
Abstract: The recent discovery of high temperature superconductivity in a layered iron arsenide has led to an intensive search to optimize the superconducting properties of iron-based superconductors by changing the chemical composition of the spacer layer that is inserted between adjacent anionic iron arsenide layers. Until now, superconductivity has only been found in compounds with a cationic spacer layer consisting of metal ions: Li+, Na+, K+, Ba2+ or a PbO-type or perovskite-type oxide layer. Electronic doping is usually necessary to control the fine balance between antiferromagnetism and superconductivity. Superconductivity has also been reported in FeSe, which contains neutral layers similar in structure to those found in the iron arsenides but without the spacer layer. Here we demonstrate the synthesis of Lix(NH2)y(NH3)1-yFe2Se2 (x ~0.6 ; y ~ 0.2), with lithium ions, lithium amide and ammonia acting as the spacer layer, which exhibits superconductivity at 43(1) K, higher than in any FeSe-derived compound reported so far and four times higher at ambient pressure than the transition temperature, Tc, of the parent Fe1.01Se. We have determined the crystal structure using neutron powder diffraction and used magnetometry and muon-spin rotation data to determine the superconducting properties. This new synthetic route opens up the possibility of further exploitation of related molecular intercalations in this and other systems in order to greatly optimize the superconducting properties in this family.

300 citations


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22 Jan 2013
TL;DR: Premises of creation of Internet portal designed to provide access to participants of educational and scientific process for the joint creation, consolidation, concentration and rapid spreading of educationaland scientific information resources in its own depository are considered.
Abstract: Premises of creation of Internet portal designed to provide access to participants of educational and scientific process for the joint creation, consolidation, concentration and rapid spreading of educational and scientific information resources in its own depository are considered. CMS-based portal content management systems’ potentiality is investigated. Architecture for Internet portal of MES of Ukraine’s information resources is offered.

969 citations

Journal ArticleDOI
TL;DR: With the flexible tuning of properties 2D TMDs become attractive candidates for a variety of applications including electronics, optoelectronics, catalysis, and energy.
Abstract: The development of two-dimensional (2D) materials has been experiencing a renaissance since the adventure of graphene. Layered transition metal dichalcogenides (TMDs) are now playing increasingly important roles in both fundamental studies and technological applications due to their wide range of material properties from semiconductors, metals to superconductors. However, a material with fixed properties may not exhibit versatile applications. Due to the unique crystal structures, the physical and chemical properties of 2D TMDs can be effectively tuned through different strategies such as reducing dimensions, intercalation, heterostructure, alloying, and gating. With the flexible tuning of properties 2D TMDs become attractive candidates for a variety of applications including electronics, optoelectronics, catalysis, and energy.

649 citations

Journal ArticleDOI
TL;DR: It is demonstrated that the superconductivity occurs when the electrons transferred from the oxygen-vacant substrate suppress the otherwise pronounced SDWs in single-layer FeSe, and the phase diagram of FeSe is mapped out as a function of lattice constant, which contains all the essential physics of Fe-HTS.
Abstract: Iron pnictide superconductors represent a suggestive alternative to cuprate superconductors for achieving high transition temperatures. Using in situ angle-resolved photoemission spectroscopy, the electronic properties of FeSe are examined as a function of film thickness, providing valuable insights into the mechanism driving the superconductivity in this material.

590 citations

Journal ArticleDOI
TL;DR: The current status of iron-based superconductors (IBSC) is described in this paper, covering most up-to-date research progress along with some background research, focusing on materials (bulk and thin film) and pairing mechanism.
Abstract: Since the discovery of high Tc iron-based superconductors in early 2008, more than 15,000 papers have been published as a result of intensive research. This paper describes the current status of iron-based superconductors (IBSC) covering most up-to-date research progress along with the some background research, focusing on materials (bulk and thin film) and pairing mechanism.

341 citations

Journal ArticleDOI
TL;DR: This review summarizes the major achievements of the project in newly found superconducting materials, and the fabrication wires and tapes of iron-based superconductors; it incorporates a list of ∼700 unsuccessful materials examined for superconductivity in the project.

311 citations