24th CEMS Colloquium

講演タイトル

ヒ素の化学を利用した高温超伝導物質の開発

講演概要

Comparable energy scale of the Cu 3d and O 2p orbitals in copper oxides provides a platform for high-temperature superconductivity, known as a charge-transfer insulator. Even in iron-based superconductors, the Fe 3d and As 4p orbitals are energetically close, which induce the breaking (making) of As-As chemical bonds depending on the filling of the Fe 3d band. CaFe₂As₂ is a typical example of this case, where superconductivity at 45 K results on the verge of As-As bond formation along the c-axis [1]. Another example is Ca₁₀(Pt₄As₈)(Fe_2-xPt_xAs₂)₅, where arsenic dimers are formed in ab-plane and superconductivity emerges at 38 K [2]. And furthermore, infinite arsenic chains can be formed in ab-plane of 112-type CaFeAs₂, where we observed superconductivity at 47 K [3].

This talk serves as an introduction to the material design for high-temperature superconductivity using the chemistry of arsenic, with the abovementioned compounds for examples.

[1] K. Kudo et al. Sci. Rep. 3, 147 (2013).
[2] S. Kakiya et al. J. Phys. Soc. Jpn. 80, 093704 (2011).
[3] K. Kudo et al. J. Phys. Soc. Jpn. 83, 093705 (2014).