论文标题
近去超导体FESE中的涡旋晶格熔化和顺磁衰变
Vortex-lattice melting and paramagnetic depairing in the nematic superconductor FeSe
论文作者
论文摘要
在两个场方向上，使用特异性加热和热扩张测量值降低到0.7 K，最高30吨，将列型超导体FESE中的完整H-T相图映射。在两个数据集中都发现了潜在涡流熔融过渡的明显热力学信号，并且可以遵循到低温。缩放分析证明了显着高斯热超导波动的存在，这也产生了平均场临界场HC2（t）。对于两个场取向，HC2（T）均显示了Pauli限制的行为。霍顿等人的模型很好地描述了涡流熔线的温度依赖性。 Rev. B 40，6763（1989）降至H $ \ perp $ fese层的最低温度，涡流熔融线对与飞机平行的田地表现出异常的行为，在那里Pauli限制的情况更强。在这里，仅观察到涡旋熔化异常，直到t*= 2-3 k，然后与Adachi和Ikeda（物理）预测的HC2（t）线合并。 Rev. B 68 184510（2003）。在T*下，HC2（T）也表现出与Fulde-Ferrell-Larkin-Ovchinnikov（FFLO）状态的发生可能相关的轻微上曲。
The full H-T phase diagram in the nematic superconductor FeSe is mapped out using specific-heat and thermal-expansion measurements down to 0.7 K and up to 30 T for both field directions. A clear thermodynamic signal of an underlying vortex-melting transition is found in both datasets and could be followed down to low temperatures. The existence of significant Gaussian thermal superconducting fluctuations is demonstrated by a scaling analysis, which also yields the mean-field upper critical field Hc2(T). For both field orientations, Hc2(T) shows Pauli-limiting behavior. Whereas the temperature dependence of the vortex-melting line is well described by the model of Houghton et al., Phys. Rev. B 40, 6763 (1989) down to the lowest temperatures for H $\perp$ FeSe layers, the vortex-melting line exhibits an unusual behavior for fields parallel to the planes, where the Pauli limitation is much stronger. Here, the vortex-melting anomaly is only observed down to T*= 2-3 K, and then merges with the Hc2(T) line as predicted by Adachi and Ikeda, Phys. Rev. B 68 184510 (2003). Below T*, Hc2(T) also exhibits a slight upturn possibly related to the occurence of a Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state.
