Study of the high temperature superconductivity of iron-chalcogenide superconductors via combining the micro-structure fabricating and ion-gating technique

我们系统地研究了用FIB拾取技术制备的FeSe c轴片的输运性质。有了这个薄片，我们可以沿着c轴放置接触点，直接测量面外输运性质。随着温度的降低，ρc在~220 K时先略有增加，然后又逐渐减小，表现出驼峰现象。这种温度依赖行为与面内电阻率ρab有很大的不同，面内电阻率ρab表现为金属行为，随着温度的升高而不断降低。此外，我们还研究了FeSe的电流-电压曲线、临界电流密度、上临界场和磁电阻，以揭示FeSe的面外电学特性。

We have performed a systematical study of the transport properties on a c-axis lamella of FeSe prepared by the FIB pick-up technique. With this lamella, we can put contacts along the c-axis, to directly measure the out-of-plane transport properties. With the decrease of temperature, ρc firstly slightly increases until ~220 K, then decreases, manifesting a hump-like behavior. Such temperature dependent behavior is quite different from the in-plane resistivity ρab, which shows a metallic behavior, continually decreasing with temperature. Besides, we also studied the current-voltage curve, critical current density, upper critical fields, and magnetoresistance to reveal the out-of-plane electrical properties of FeSe.