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arXiv · 2309.01295

Study on Susceptibilities of Superconductors BaPtSb and BaPtAs with Honeycomb Structure

Naoya Furutani·Yoshiki Imai·Tsuyoshi Imazu·Jun Goryo
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Abstract

The low-energy electronic properties of the new superconductors BaPtSb and BaPtAs with an ordered honeycomb network are investigated in the normal phase, where the former compound is a candidate for time-reversal symmetry-breaking superconductors. By means of the first-principles calculation, we show that there exist two-dimensional cylinder-like Fermi surfaces around the kz axis and one outer spherelike Fermi surface around the K and K' points in both compounds, which are mainly composed of Pt 5d and Sb 5p/As 4p electrons. We construct low-energy effective models, which are well described by using three bands consisting of two Pt 5d orbitals and one Sb 5p/As 4p orbital. By evaluating susceptibilities using effective models, we find that dominant contributions to those susceptibilities result from the outer spherelike Fermi surface. Whereas out-of-plane fluctuations are enhanced in both compounds in the higher-temperature region, in-plane fluctuations become dominant in the very low-temperature region in BaPtSb owing to a better nesting condition in the k_z=0 plane from the outer spherelike Fermi surface. These fluctuations yield instabilities to ordered states, such as superconductivity, and might be associated with the occurrence of the superconducting state with time-reversal symmetry breaking in BaPtSb.

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Naoya Furutani, Yoshiki Imai, Tsuyoshi Imazu, Jun Goryo. 2023-09-04. Study on Susceptibilities of Superconductors BaPtSb and BaPtAs with Honeycomb Structure. https://doi.org/10.7566/jpsj.92.094708

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