Tuning Triplet Superconductivity States at LSMO/YBCO Interfaces

Triplet superconductivity at a high-T_c-superconductor/Ferromagnetic-oxide (SC/FM) interface potentially has a significant impact on the development of spintronics, quantum information, and the search for Majorana fermions. Triplet superconductivity has three states: s_z=0 and ±1. The s_z=0 state, also known as the FFLO state, exhibits short penetration depth and its wave function oscillates over a short distance within the ferromagnetic layer. In contrast, the s_z=±1 states have a long penetration depth and can be considered a dissipationless spin-polarized current. To tune the superconductivity within these states, an additional interfacial layer with a magnetic moment perpendicular to that of the ferromagnetic layer is proposed. We have discovered that the induced Cu moment at the interface may function as the magnetic interfacial layer. Furthermore, its magnetic moment direction can be controlled by using a field-cooling process with a specific range of fields. The orientation of the Cu moment can be altered by disrupted flipping between three different alignments with respect to that of the FM layer. With an appropriately applied field during the field-cooling process, we observed a significant enhancement of the superconducting critical current due to the generation of triplet superconductivity at s_z= ±1. In this presentation, we will present the transport measurements to elucidate the collective behavior and polarized neutron reflectivity to reveal the interface conditions.