Transportation of Quasistatic Magnetic Fields by Superconductor-Ferromagnet Heterostructures

We have devised a magnetic circuit for improved transport of quasistatic magnetic fields from a transmitter to a receiver in order to increase the transfer efficiency of electromagnetic devices such as transformers. This novel structure is made by coating a superconductor-ferromagnet heterostructure on a traditionally used magnetic core. We tested the transfer efficiency of the proposed magnetic circuit in transporting ac current from the primary to the secondary coils, which could be regarded as a proof-of-principle demonstration of the current transformer. The measured and calculated results clearly show that the proposed current transformer could transport current to the secondary coil with much higher efficiency than a conventional naked magnetic core. Characterization of the current transformer shows a dependence of transfer efficiency on the amplitude and frequency of the primary current. The results could also be applied to enhance the efficiency of voltage transformers, which rely on the same principle as the current transformer.