Effects of Metallic Spacer in Layered Superconducting Sr-2(MgyTi1-y)O3FeAs
- Authors
- Lee, Kwan-Woo
- Issue Date
- 5월-2013
- Publisher
- SPRINGER
- Keywords
- Superconductivity; Fe-pnictides; Electronic structure; Fermiology
- Citation
- JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM, v.26, no.5, pp.1977 - 1982
- Indexed
- SCIE
SCOPUS
- Journal Title
- JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM
- Volume
- 26
- Number
- 5
- Start Page
- 1977
- End Page
- 1982
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/103409
- DOI
- 10.1007/s10948-012-2066-3
- ISSN
- 1557-1939
- Abstract
- The highly two-dimensional superconducting system Sr-2(MgyTi1-y)O3FeAs, recently synthesized in the range of 0.2 <= y <= 0.5, shows an Mg concentration-dependent T-c. Reducing the Mg concentration from y = 0.5 leads to a sudden increase in T-c, with a maximum T-c approximate to 40 K at y = 0.2. Using first principles calculations, the unsynthesized stoichiometric y = 0 and the substoichiometric y = 0.5 compounds have been investigated. For the 50 % Mg-doped phase (y = 0.5), Sr-2(MgyTi1-y)O-3 layers are completely insulating spacers between FeAs layers, leading to the fermiology such as that found for other Fe pnictides. At y = 0, representing a phase with metallic Sr2TiO3 layers, the Gamma-centered Fe-derived Fermi surfaces (FSs) considerably shrink or disappear. Instead, three Gamma-centered Ti FSs appear, and in particular two of them have similar size, like in MgB2. Interestingly, FSs have very low Fermi velocity in large fractions: the lowest being 0.6 x 10(6) cm/s. Furthermore, our fixed spin moment calculations suggest the possibility of magnetic ordering, with magnetic Ti and nearly nonmagnetic Fe ions. These results indicate a crucial role of Sr-2(MgyTi1-y)O-3 layers in this superconductivity.
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Collections - College of Science and Technology > Semiconductor Physics in Division of Display and Semiconductor Physics > 1. Journal Articles
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