Crossover between different regimes of inhomogeneous superconductivity in planar superconductor-ferromagnet hybrids
Crossover between different regimes of inhomogeneous superconductivity in planar superconductor-ferromagnet hybrids
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DOI：
10.1103/physrevb.84.094523
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发表时间：
2011-05
影响因子：
3.7
通讯作者：
A. Aladyshkin;J. Fritzsche;R. Werner;R. Kramer;S. Guénon;R. Kleiner;D. Koelle;V. Moshchalkov
中科院分区：
文献类型：
--
作者：
A. Aladyshkin;J. Fritzsche;R. Werner;R. Kramer;S. Guénon;R. Kleiner;D. Koelle;V. Moshchalkov
实验研究了铁磁BaFe_{12}O_{19}衬底中的条状畴结构对超导Pb微桥磁电阻的影响。该系统被设计成使得桥垂直于畴壁定向。结果表明，取决于铁磁体感应的非均匀磁场B_0的幅值与超导材料的上临界场H_{c2}的比值，H-T平面内的反畴超导区域可以是孤立的，也可以是重叠的（H为外磁场，T为温度）。后一种情况对应于B_0/H_{c2}<1的条件，并导致在两个极性的磁畴之上形成超导性。我们发现了边缘辅助的反畴超导性的制度，对应于局部超导性的边缘附近的桥以上的补偿磁畴。通过低温扫描激光显微镜直接验证了非均匀超导态的形成以及外场控制的正常态和非均匀超导态之间的切换。
We studied experimentally the effect of a stripe-like domain structure in a ferromagnetic BaFe_{12}O_{19} substrate on the magnetoresistance of a superconducting Pb microbridge. The system was designed in such a way that the bridge is oriented perpendicular to the domain walls. It is demonstrated that depending on the ratio between the amplitude of the nonuniform magnetic field B_0, induced by the ferromagnet, and the upper critical field H_{c2} of the superconducting material, the regions of the reverse-domain superconductivity in the H-T plane can be isolated or can overlap (H is the external magnetic field, T is temperature). The latter case corresponds to the condition B_0/H_{c2}<1 and results in the formation of superconductivity above the magnetic domains of both polarities. We discovered the regime of edge-assisted reverse-domain superconductivity, corresponding to localized superconductivity near the edges of the bridge above the compensated magnetic domains. Direct verification of the formation of inhomogeneous superconducting states and external-field-controlled switching between normal state and inhomogeneous superconductivity were obtained by low-temperature scanning laser microscopy.