论文标题
反底酮氧化物超导体SR $ _ {3-X} $ SNO $μ$ SR揭示的渗透深度和间隙结构
Penetration depth and gap structure in the antiperovskite oxide superconductor Sr$_{3-x}$SnO revealed by $μ$SR
论文作者
论文摘要
我们报告了一项关于Antiperovskite氧化物超导体SR $ _ {3-X} $ SNO的$μ$ SR研究。使用横向场$μ$ sr，我们观察到在冷却以下时，在超导过渡温度以下$ t _ {\ mathrm {c}} = 5.4 $ k时，会增加μ子松弛率。在低温下，松弛率$σ$的指数温度依赖性表明超导性状态。我们评估了零温度的穿透深度$λ（0）\ propto1/\ sqrt {σ（0）} $，约为320-1020 nm。如此大的价值与掺杂的狄拉克半学的图片一致。此外，我们揭示了比率$ t _ {\ mathrm {c}}/λ（0）^{ - 2} $比普通超导体的比率大，并且与非常规超导体的比率相当。对于小载体密度，相对较高的$ t _ {\ mathrm {c}} $可能会暗示超出普通声子介导的配对以外的非常规的配对机制。此外，零场$μ$ SR没有提供超导状态下时间反转对称性断裂的证据。这些功能与SR $ _ {3-X} $ SNO中的理论上提出的拓扑超导状态以及$ S $ - 波超导率一致。
We report a $μ$SR study on the antiperovskite oxide superconductor Sr$_{3-x}$SnO. With transverse-field $μ$SR, we observed the increase of the muon relaxation rate upon cooling below the superconducting transition temperature $T_{\mathrm{c}}=5.4$ K, evidencing bulk superconductivity. The exponential temperature dependence of the relaxation rate $σ$ at low temperatures suggests a fully gapped superconducting state. We evaluated the zero-temperature penetration depth $λ(0)\propto1/\sqrt{σ(0)}$ to be around 320-1020 nm. Such a large value is consistent with the picture of a doped Dirac semimetal. Moreover, we revealed that the ratio $T_{\mathrm{c}}/λ(0)^{-2}$ is larger than those of ordinary superconductors and is comparable to those of unconventional superconductors. The relatively high $T_{\mathrm{c}}$ for small carrier density may hint at an unconventional pairing mechanism beyond the ordinary phonon-mediated pairing. In addition, zero-field $μ$SR did not provide evidence of broken time-reversal symmetry in the superconducting state. These features are consistent with the theoretically proposed topological superconducting state in Sr$_{3-x}$SnO, as well as with $s$-wave superconductivity.
