PC5-5

Superconductivity in (Sc1-xLux)6FeTe2 with Ordered Fe2P Structure

16:15-16:30 Dec.4

*Tsuyoshi Tamegai, WENJIE LI, Shunsuke Itabashi, Ryosuke Sakagami
The University of Tokyo
Abstract Body

Superconductivity with Tc ~4.7 K was discovered in Sc6FeTe2 with ordered Fe2P structure in 2023 [1]. One of peculiar feature of Sc6FeTe2 is the existence of residual electronic specific heat of ~40% of the normal state value even at 0.5 K. A similar residual electronic specific heat has been reported in Lu2Fe3Si5 with Tc ~6.0 K. However, later specific heat measurements down to 0.4 K demonstrated the existence of second drop of electronic specific heat at lower temperatures [2], and Lu2Fe3Si5 is considered to be a typical two-gap superconductor similar to MgB2. In order to elucidate the origin of residual specific heat and evolution of superconductivity in Sc6FeTe2, we have prepared polycrystalline samples of (Sc1-xLux)6FeTe2. X-ray diffraction patterns shown in the Fig. 1 demonstrate that Sc can be fully replaced by Lu, although peaks originated from (Sc,Lu)-alloy become stronger with x. On the other hand, Tc is quickly suppressed with x, and it becomes lower than 2 K at x = 0.2. Contrary to this result, point defects created by 3 MeV proton irradiation do not suppressing Tc appreciably in Sc6FeTe2, supporting single-gap s-wave superconductivity. The origin of the residual specific heat in Sc6FeTe2 is considered to be originated from the phase-separated Sc impurity phase.

[1] Y. Shinoda et al, J. Phys. Soc. Jpn. 92, 103701 (2023).

[2] Y. Nakajima et al., Phys. Rev. Lett. 100, 1570010 (2008).

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