Fine tuning APC concentration in REBCO coated conductors through surface modified target method

摘要

Increased critical current density in higher applied magnetic fields is highly desired for REBCO thin films on textured substrates for widespread technological applications. Many methods have been successfully used to improve the critical current properties of REBCO films by incorporating artificial pinning centers (APCs). A novel approach for APC incorporation in REBCO films using pulsed laser deposition technique is to use surface modified target method in which a thin sectored/rectangular shaped piece of secondary phase material is attached onto the top of REBCO target using silver paste. As the target is rotated, both REBCO and APC material portions are alternatively ablated by high energy laser pulses. The advantages of this method are that the REBCO portion and APC material portion are physically separate and the APC concentration can be finely tuned by changing the size of the sectored/rectangular shaped piece of the APC material while keeping the REBCO target as the same. The fine tuning of the APC concentration is very important from the point of view of the critical current performance being critically dependent on the APC concentration as investigated recently. The schematic diagram of the surface modified target and the top view of the actual target being used are shown in figure 1.