16th International Conference on Muon Spin Rotation, Relaxation and Resonance (μSR2025)

Superconductivity and Magnetism of Dirac-Semimetal CaSb2 and EuSb2

Not scheduled

20m

Poster Presentation Superconductivity Poster session 2

Speakers

Kenji Kojima (TRUIMF) Mohamed Oudah (SBQMI, UBC)

Description

CaSb2 has been identified as a topological semimetal [1] and a bulk superconductor[2,3]. We investigate the superconducting state and the spontaneous magnetism using muon spin-relaxation (µSR) [4]. Zero-field muon relaxation shows little temperature dependence when the muon-spin is parallel to the c∗-axis, while an increase in relaxation appears below 1 K when the muon-spin is parallel to the ab-plane [4]. This suggests an emergence of a second superconducting phase with a loop-current on the ab-plane below the bulk Tc = 1.55 K.
EuSb2 is also a topological semimetal [5], but with a magnetic order of Eu2+ (S=7/2) at the Neel temperature TN=26.5K [6]. The Weiss temperature θ = -0.32 K is anomalously small, suggesting a competition between the ferromagnetic and the antiferromagnetic interactions within and between the zig-zag chains. Zero-field µSR observed two precession frequencies with the identical amplitudes, but with one of them showing an anomalous temperature dependence [7]. We discuss the origin of the anomaly in relation to the tricritical point of ferro- and antiferro-magnetic interactions.

[1] K. Funada, et al., JPSJ, 88, 044711 (2019).
[2] A. Ikeda, et al., PRM, 4, 041801(R) (2020).
[3] M. Oudah, et al., PRB, 105, 184504 (2022).
[4] M. Oudah, et al., PRB, 110, 134524 (2024).
[5] M. Ohno, et al. Phys. Rev. B 103, 165144 (2021).
[6] F. Hulliger, and R. Schmelczer. J. Solid State Chem., 26, 389 (1978).
[7] M. Oudah, et al., in preparation.