Mn₅Si₃约瑟夫森结中超导电流的快速衰减
Rapid supercurrent decay in Mn$_5$Si$_3$ Josephson junctions
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中文总结 AI 辅助
本文针对Mn₅Si₃约瑟夫森结，制备并测量不同势垒厚度的器件，发现其超导电流快速衰减且未观测到0-π转变，明确了未来测试交替磁约瑟夫森物理需采用晶向明确的势垒。
中文摘要 AI 辅助
理论研究预测，包含金属交替磁势垒的约瑟夫森结应呈现临界电流随势垒厚度和温度变化的0-π转变，超导电流的衰减和振荡周期取决于晶轴相对于输运方向的取向。受这些预测以及外延Mn₅Si₃薄膜中存在归因于交替磁性的补偿磁相的报道的启发，我们制备并测量了Nb/Pt/Mn₅Si₃/Pt/Nb约瑟夫森结，改变Mn₅Si₃势垒的厚度。临界电流以单指数形式衰减，衰减幅度超过四个数量级，衰减长度ξ_{Mn₅Si₃}=0.31±0.03nm，短于包含金属反铁磁体FeMn、Cr和NiMn的约瑟夫森结的报道值。Mn₅Si₃势垒的垂直平面电阻率估计为320±10μΩ·cm。在采样的势垒厚度下未观测到可分辨的0-π转变，且势垒厚度为1nm的结的临界电流随温度的变化是平滑且单调的。我们从势垒的微观结构、其不确定的磁相以及快速衰减所施加的窄厚度窗口的角度讨论了可分辨转变的缺失，并确定具有明确晶向的势垒是未来测试交替磁约瑟夫森物理的关键要求。
英文摘要
Theoretical work predicts that Josephson junctions containing metallic altermagnetic barriers should display $0$-$π$ transitions of the critical current as a function of both barrier thickness and temperature, with the decay and oscillation period of the supercurrent depending on the orientation of the crystal axes relative to the transport direction. Motivated by these predictions, and by reports of a compensated magnetic phase attributed to altermagnetism in epitaxial Mn$_5$Si$_3$ thin films, we fabricate and measure Nb/Pt/Mn$_5$Si$_3$/Pt/Nb Josephson junctions varying the thickness of the Mn$_5$Si$_3$ barrier. The critical current decays as a single exponential over more than four orders of magnitude with decay length $ξ_{\text{Mn}_5\text{Si}_3} = 0.31 \pm 0.03$ nm, shorter than reported for Josephson junctions containing the metallic antiferromagnets FeMn, Cr, and NiMn. The Mn$_5$Si$_3$ barrier has an estimated current-perpendicular-to-plane resistivity of $320 \pm 10 μΩ\,$cm. No $0$-$π$ transition is resolved at the sampled barrier thicknesses, and the temperature dependence of the critical current of a junction with a 1 nm barrier is smooth and monotonic. We discuss the absence of resolvable transitions in terms of the microstructure of the barrier, its uncertain magnetic phase, and the narrow thickness window imposed by the rapid decay, and identify barriers with well-defined crystalline orientation as the key requirement for future tests of altermagnetic Josephson physics.
