Temperature-induced crossover between0andπstates in S/F/S junctions
Temperature-induced crossover between0andπstates in S/F/S junctions
复制标题
S/F/S 结中温度引起的 0 态和 π 态之间的交叉
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
R. Calemczuk
中科院分区：
文献类型：
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作者：
H. Sellier;C. Baraduc;F. Lefloch;R. Calemczuk
铁磁约瑟夫森结在平衡状态下超导电极之间会出现π相位差。我们用一个由交换能移动的Andreev束缚态的修正谱来解释这个π态。计算了谱超电流密度的简化表达式，并讨论了临界电流的非单调温度依赖性。该模型占取消的临界电流与温度在我们的Nb/Cu 5 2 Ni 4 8 /Nb结的势垒厚度的小范围内观察到。这种抵消对应于超电流的反转和从0态到π态的基态交叉。这种转变是由准粒子的热分布和交换能量的温度依赖性引起的。实验曲线很好地再现了我们的理论表达式，除了非常小的振幅的超电流归因于一个大的自旋翻转散射。
Ferromagnetic Josephson junctions can show at equilibrium a π phase difference between the superconducting electrodes. We explain this π state in an original way by a modified spectrum of Andreev bound states shifted by the exchange energy. A simplified expression for the spectral supercurrent density is calculated and the nonmonotonic temperature dependence of the critical current is discussed. This model accounts for the cancellation of the critical current with temperature observed in a small range of barrier thickness in our Nb/Cu 5 2 Ni 4 8 /Nb junctions. This cancellation corresponds to an inversion of the supercurrent and to a ground-state crossover from a 0 state to a π state. This transition is caused both by the thermal distribution of quasiparticles and by the temperature dependence of the exchange energy. The experimental curves are well reproduced by our theoretical expression except for the very small amplitude of the supercurrent attributed to a large spin-flip scattering.