Sharp magnetization jump at the first-order superconducting transition in Sr2RuO4

Shunichiro Kittaka; Akira Kasahara; Toshiro Sakakibara; Daisuke Shibata; Shingo Yonezawa; Yoshiteru Maeno; Kenichi Tenya; Kazushige Machida

doi:10.1103/PhysRevB.90.220502

paper

Sharp magnetization jump at the first-order superconducting transition in Sr2RuO4

arXiv:1410.0798 · doi:10.1103/PhysRevB.90.220502

Abstract

The magnetization and magnetic torque of a high-quality single crystal of Sr $_{2}$ RuO $_{4}$ have been measured down to 0.1 K under a precise control of the magnetic-field orientation. When the magnetic field is applied exactly parallel to the $ab$ plane, a sharp magnetization jump $4 π δ M$ of $(0.74 \pm 0.15)$ G at the upper critical field $H_{c2, ab} \sim 15$ kOe with a field hysteresis of 100 Oe is observed at low temperatures, evidencing a first-order superconducting-normal transition. A strong magnetic torque appearing when $H$ is slightly tilted away from the $ab$ plane confirms an intrinsic anisotropy $Γ = ξ_{a} / ξ_{c}$ of as large as 60 even at 100 mK, in contrast with the observed $H_{c2}$ anisotropy of $\sim 20$ . The present results raise fundamental issues in both the existing spin-triplet and spin-singlet scenarios, providing, in turn, crucial hints toward the resolution of the superconducting nature of Sr $_{2}$ RuO $_{4}$ .

5 pages, 4 figures (main text) + 2 pages, 2 figures (supplemental material), published in Phys. Rev. B

Sharp magnetization jump at the first-order superconducting transition in Sr2RuO4

Abstract

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