A method to access the electro-mechanical properties of superconducting thin film under uniaxial compression

Abstract

Superconducting thin films are widely used in superconducting quantum interferometers, microwave devices, etc. The electrical performance of a superconducting thin film is often affected by structural deformation or stress. Based on four-point bending of a Cu-Be beam, we constructed a device that could apply uniaxial, uniform, compressive strain to a superconducting thin film at both room temperature and the temperature of liquid nitrogen. The thin film was placed into a slot carved in the Cu-Be beam. We optimized the size of this slot via numerical simulation. Our results indicated that the slot width was optimal when it was same as the width of the Cu-Be beam. Notably, the sample bended hardly after machining two slits along width direction on both sides of the slot. A YBa2Cu3O7-δ-SrTiO3 (YBCO-STO) film was used as an example. It was loaded by the aforementioned device to determine its electrical characteristics as functions of the uniaxial-uniform-compressive strain. The optimized design allowed the sample to be compressed to a larger strain without breaking it.