Scalable superconducting memory with a pseudo-spin-valve barrier
The quantum behavior of Josephson junctions is often exploited to produce superconducting devices of outstanding performance. With respect to information technology applications, Josephson junctions can be used in circuits that perform logic operations in picoseconds, which may result in energy-efficient, high-performance cryogenic computers, provided that memory elements can be developed that can be switched between two stable states by integrated superconducting logic circuits. Here, we show that Josephson junctions based on pseudo-spin-valve barriers could enable such memory elements, by unambiguously differentiating the controlled changes in Josephson coupling from size-dependent remanent-field effects. These changes can be very large and even reversed in magnitude, which is strong evidence of the exchange-field effect on the Cooper pair phase. These devices are the first that demonstrate nonvolatile, size-independent switching of the Josephson coupling in magnitude or phase, and they may allow for the first scalable superconducting memory devices.