We develop superconducting quantum interference device (SQUID) probes based on 3D nano-bridge junctions for the scanning SQUID microscopy. The use of these nano-bridge junctions enables imaging in the presence of a high magnetic field. Conventionally, a superconducting ground layer has been employed for better magnetic shielding. In our study, we prepare a number of scanning SQUID probes with and without a ground layer to evaluate their performance in external magnetic fields. The devices show the improved magnetic modulation up to 1.4 T. It is found that the ground layer reduces the inductance, and increases the modulation depth and symmetricity of the gradiometer design in the absence of the field. However, the layer is not compatible with the use of the scanning SQUID probe in the field because it decreases its working field range. Moreover, by adding the layer, the mutual inductance between the feedback coil and the SQUID also decreases linearly as a function of the field.

中文翻译：

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磁场中基于3D纳米桥结的扫描SQUID探针的表征

我们基于3D纳米桥结开发了用于扫描SQUID显微镜的超导量子干涉仪（SQUID）探针。这些纳米桥结的使用使得能够在存在高磁场的情况下进行成像。常规地，已经采用超导接地层以更好地磁屏蔽。在我们的研究中，我们准备了许多带有或不带有接地层的SQUID扫描探头，以评估它们在外部磁场中的性能。器件显示了高达1.4 T的改进的磁调制性能。发现在没有磁场的情况下，接地层减小了电感，并增加了梯度计设计的调制深度和对称性。但是，该层与扫描SQUID探头在现场的使用不兼容，因为它会减小其工作范围。此外，