Reconfigurable Logic Gate of Quantum-Flux-Parametron Using Magnetic Material

We propose reconfigurable quantum-flux-parametron (QFP) circuit using a magnetic material for program devices such as a field-programmable gate array (FPGA). A three-input majority gate is the basic element for QFP logic circuits. We obtain two-input AND or OR gate by keeping one of the inputs logical value of 0 or 1, respectively. We use a ferromagnetic film pattern deposited on the input wiring of the majority gate, and magnetize to apply a magnetic flux. By changing the direction of magnetization, we reconfigure the functions of the gate. We fabricated the reconfigurable QFP gate to demonstrate the function switching, and to investigate the required magnetization strength. We deposited 70- nm thick PdNi film with a Curie temperature of 110 K on the QFP circuits and patterned it. We applied an external magnetic field for magnetizing the PdNi pattern when we cooled the circuit. We successfully obtained OR and AND functions for the magnetic field in a range of -1800 to -1500 μT, and -1200 to 300 μT, respectively.