The electronic and superconducting properties of Fe_1–δ Se single-crystal flakes grown hydrothermally are studied by the transport measurements under zero and high magnetic fields up to 38.5 T. The results contrast sharply with those previously reported for nematically ordered FeSe by chemical-vapor-transport (CVT) growth. No signature of the electronic nematicity, but an evident metal-to-nonmetal crossover with increasing temperature, is detected in the normal state of the present hydrothermal samples. Interestingly, a higher superconducting critical temperature T _c of 13.2 K is observed compared to a suppressed T _c of 9 K in the presence of the nematicity in the CVT FeSe. Moreover, the upper critical field in the zero-temperature limit is found to be isotropic with respect to the field direction and to reach a higher value of ∼42 T, which breaks the Pauli limit by a factor of 1.8.

通过在零磁场和高达 38.5 T 的高磁场下的传输测量研究了水热生长的 Fe _{1– δ} Se 单晶薄片的电子和超导特性。结果与先前通过化学蒸汽报道的向列有序 FeSe 的结果形成鲜明对比-运输（CVT）增长。在目前的热液样品的正常状态下，没有检测到电子向列性的特征，但随着温度的升高存在明显的金属到非金属交叉。有趣的是，与抑制的T _c相比，观察到 13.2 K的更高超导临界温度T _c 在 CVT FeSe 中存在向列性的情况下为 9 K。此外，发现零温度极限中的上临界场相对于场方向是各向同性的，并达到~42 T 的更高值，这将泡利极限打破了 1.8 倍。