Oxygen vacancy is known to play an important role for the physical properties in SrTiO₃(STO)-based systems. On the surface, rich structural reconstructions had been reported owing to the oxygen vacancies, giving rise to metallic surface states and unusual surface phonon modes. More recently, an intriguing phenomenon of a huge superconducting transition temperature enhancement was discovered in a monolayer FeSe on STO substrate, where the surface reconstructed STO (SR-STO) may play a role. In this work, SR-STO substrates were prepared via thermal annealing in ultra-high vacuum followed by low energy electron diffraction analyses on surface structures. Thin Nb films with different thicknesses (d) were then deposited on the SR-STO. The detailed studies of the magnetotransport and superconducting property in the Al(1 nm)/Nb(d)/SR-STO samples revealed a large positive magnetoresistance and a pronounced resistance peak near the onset of the resistive superconducting transition in the presence of an in-plane field. Remarkably, the amplitude of the resistance peak increases with increasing fields, reaching a value of nearly 57% of the normal state resistance at 9 T. Such resistance peaks were absent in the control samples of Al(1 nm)/Nb(d)/STO and Al(1 nm)/Nb(d)/SiO₂. Combining with DFT calculations for SR-STO, we attribute the resistance peak to the interface resistance from the proximity coupling of the superconducting niobium to the field-enhanced long-range magnetic order in SR-STO that arises from the spin-polarized in-gap states due to oxygen vacancies.

已知氧空位在基于SrTiO ₃（STO）的系统中对物理性能起重要作用。在表面上，由于氧空位，已经报道了丰富的结构重建，从而产生了金属表面态和不寻常的表面声子模式。最近，在STO基板上的单层FeSe中发现了一个有趣的超导过渡温度升高现象，表面重建的STO（SR-STO）可能在其中起作用。在这项工作中，通过在超高真空中进行热退火，然后在表面结构上进行低能电子衍射分析，来制备SR-STO基板。不同厚度的Nb薄膜（d）然后存放在SR-STO上。对Al（1 nm）/ Nb（d）/ SR-STO样品中的磁输运和超导性能的详细研究表明，在存在In的情况下，在电阻性超导转变的开始附近有很​​大的正磁阻和明显的电阻峰。平面场。值得注意的是，电阻峰的幅度随电场的增加而增加，在9 T时达到正常状态电阻的近57％。在Al（1 nm）/ Nb（d）/ STO和Al（1 nm）/ Nb（d）/ SiO ₂。结合SR-STO的DFT计算，我们将电阻峰值归因于超导铌的邻近耦合引起的界面电阻到SR-STO中自旋极化的带隙内产生的场增强远距离磁阶由于氧空位。