HTS Multimaterial Gradiometer Modules for YBa2Cu3O7 SQUID Systems

For the measurement of very small magnetic fields, systems based on superconducting quantum-interference devices (SQUIDs) have been manufactured and employed for many years. In liquid helium operated systems with niobium SQUIDs, wire wound gradiometers can be coupled to a shielded SQUID, but in ceramic high-temperature superconductors (HTS) this is not a common setup, since appropriate thin HTS wires with a bending radius of millimeters operating at liquid nitrogen temperature and the corresponding joining technology is not easily available. We investigated the potential of additive manufacturing to fabricate hybrid plastic and ceramic structures of the insulating perovskite SrTiO3 together with the high- Tc superconductor YBa2Cu3O7, reaching a $T_{c}$ of up to 84 K in the 3D-printed polycrystalline materials. With our measurement setup, the structures are characterized in terms of $T_{c}$ and $I_{c}$ . With the successful process, now larger sample sizes and arbitrary hybrid structures can be manufactured. A gradiometric pick-up loop was fabricated and characterized. These structures can be integrated in low-noise plastic holders and encapsulated by plastic-printed capsules to protect the HTS devices from humidity. By additive manufacturing very versatile ceramic HTS multimaterial hybrid modules can be employed for novel HTS SQUID systems.