Browsing by Author "Miura, A"

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    Fe Site order and magnetic properties of Fe1/4NbS2
    (American Chemical Society (ACS), 2023-11-06) Lawrence, EA; Huai, XD; Kim, DW; Avdeev, M; Chen, Y; Skorupskii, G; Miura, A; Ferrenti, A; Waibel, M; Kawaguchi, S; Ng, N; Kaman, B; Cai, Z; Schoop, L; Kushwaha, S; Liu, F; Tran, TT; Ji, H
    Transition-metal dichalcogenides (TMDs) have long been attractive to researchers for their diverse properties and high degree of tunability. Most recently, interest in magnetically intercalated TMDs has resurged due to their potential applications in spintronic devices. While certain compositions featuring the absence of inversion symmetry such as Fe1/3NbS2 and Cr1/3NbS2 have garnered the most attention, the diverse compositional space afforded through the host matrix composition as well as intercalant identity and concentration is large and remains relatively underexplored. Here, we report the magnetic ground state of Fe1/4NbS2 that was determined from low-temperature neutron powder diffraction as an A-type antiferromagnet. Despite the presence of overall inversion symmetry, the pristine compound manifests spin polarization induced by the antiferromagnetic order at generic k points, based on density functional theory band-structure calculations. Furthermore, by combining synchrotron diffraction, pair distribution function, and magnetic susceptibility measurements, we find that the magnetic properties of Fe1/4NbS2 are sensitive to the Fe site order, which can be tuned via electrochemical lithiation and thermal history. © 2023 American Chemical Society.
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    Hydrothermal synthesis, crystal structure, and superconductivity of a double-perovskite Bi oxide
    (American Chemical Society, 2015-12-23) Rubel, MHK; Takei, T; Kumada, N; Ali, MM; Miura, A; Tadanaga, K; Oka, K; Azuma, M; Yashima, M; Fujii, K; Magome, E; Moriyoshi, C; Kuroiwa, Y; Hester, JR; Avdeev, M
    Double-perovskite Bi oxides are a new series of superconducting materials, and their crystal structure and superconducting properties are under investigation. In this paper, we describe the synthesis and characterization of a new double-perovskite material that has an increased superconductive transition temperature of 31.5 K. The structure of the material was examined using powder neutron diffraction (ND), synchrotron X-ray diffraction (SXRD), and transmission electron microscopy (TEM). Rietveld refinement of the sample based on ND and SXRD data confirmed an A-site-ordered (K1.00)(Ba1.00)3(Bi0.89Na0.11)4O12 double-perovskite-type structure with the space group Im3̅m (No. 229). This structural analysis revealed the incorporation of Na with Bi in the structure and a bent bond between (Na, Bi)–O–(Na, Bi). TEM analyses also confirmed a cubic double-perovskite structure. This hydrothermally synthesized compound exhibited a large shielding volume fraction, exceeding 100%, with onset of superconductivity at ∼31.5 K. Its electrical resistivity dropped near onset at ∼28 K, and zero resistivity was confirmed below 13 K. The calculated band structure revealed that the metallicity of the compound and the flatness of the conduction bands near the Fermi level (EF) are important for the appearance of superconductivity. © 2015 American Chemical Society
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    A layered wide-gap oxyhalide semiconductor with an infinite ZnO2 square planar sheet: Sr2ZnO2Cl2
    (Royal Society of Chemistry, 2017-03-13) Su, Y; Tsujimoto, Y; Miura, A; Asai, S; Avdeev, M; Ogino, H; Ako, M; Belik, AA; Masuda, T; Uchikoshi, T; Yamaura, K
    A new square-planar zinc oxyhalide, Sr2ZnO2Cl2, was successfully synthesized using a high-pressure method. Absorption spectroscopy revealed an indirect band gap of 3.66 eV. Electronic structure calculations indicated a strong hybridization between Zn 3dx2−y2 and O 2p orbitals, which is distinct from tetrahedrally coordinated ZnO. © Royal Society of Chemistry 2021