人工ピンニングによるREBCO 薄膜の臨界電流特性改善

抄録

Nanorods and nanoparticles are commonly introduced to REBCO coated conductors as artificial pinning centers to improve the critical current density in high magnetic fields and to reduce the anisotropy with respect to the magnetic field angle. In this article the pinning properties are theoretically analyzed based on the classic condensation energy pinning interaction mechanism (δT_c pinning) of these pinning centers and the results are compared with experimental results. The agreements show that the critical current density can be designed by controlling the microstructure of pinning centers and factors such as the size, number density and morphology. It is also pointed out that the upper critical field is enhanced via the electron scattering of the interface between the pinning center and the superconducting matrix. Hence, the upper critical field can also be controlled to enhance the irreversibility field by controlling the interface area in a unit volume of the superconductor. It is expected that the high field performance can be optimized by controlling the pinning strength and the upper critical field in the future.