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SM ISO690:2012 CROITORI, Dorina, FILIPPOVA, Irina, KRAVTSOV, Victor, GUNTHER, A., WIDMANN, S., REUTER, Daniel, KRUG VON NIDDA, Hans Albrecht, DEISENHOFER, Joachim, LOIDL, Alois, TSURKAN, Vladimir. Structure, superconductivity, and magnetism in Rb1-xFe1.6Se2-z Sz. In: Physical Review B, 2020, vol. 101, p. 0. ISSN 2469-9950. DOI: https://doi.org/10.1103/PhysRevB.101.054516 |
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Physical Review B | ||||||
Volumul 101 / 2020 / ISSN 2469-9950 /ISSNe 2469-9969 | ||||||
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DOI:https://doi.org/10.1103/PhysRevB.101.054516 | ||||||
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We report on single-crystal growth, stoichiometry, structure and basic characterization of Rb1-xFe2-ySe2-zSz crystals where Se is substituted by S. The temperature and magnetic field dependence of magnetic and thermodynamic properties of all samples was studied by differential-scanning calorimetry, magnetic susceptibility, electrical conductivity, and specific heat. The experimental results are discussed within a T-z phase diagram, which includes vacancy-ordered and vacancy-disordered antiferromagnetic (AFM), superconducting (SC), and nonsuperconducting phases. The structural study reveals change in the local environment of the Fe tetrahedrons depending on substitution: A reduction of the Fe-Fe and Fe-Ch(chalcogen) bond lengths and a tendency for six out-of eight bond angles to approach values realizing a regular tetrahedron and hence, suggesting a reduction of structural distortions with substitution. With increasing substitution, a nonmonotonic decrease of the superconducting transition temperature Tc was observed; the SC state disappears at a substitution level above z=1.2. The SC state coexists with the AFM state that persists in all samples independent of substitution. The transition temperature into the AFM state, TN, decreases gradually with increasing substitution indicating a weakening of the AFM interactions. The AFM phase exhibits an iron-vacancy-ordered structure below the structural transition temperature Ts. Ts shows a nonmonotonous variation: A decrease with increasing z up to 1.3, followed by an increase on further increasing z. The electronic specific heat reveals a significant reduction of the anomaly at the SC transition temperature indicating a reduction of the density of states at the Fermi energy and a weakening of the electronic correlations that can explain the suppression of the superconductivity with substitution. |
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Cuvinte-cheie Binary alloys, crystal structure, differential scanning calorimetry, magnetic susceptibility, magnetism, Phase transitions, reduction, Rubidium compounds, single crystals, Specific heat of solids, Superconducting transition temperature |
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