Abstract

The promise of spin-electronics (spintronics) is that logic processing based on the spin of an electron can be faster and lower power than the conventional charge-based equivalent in semiconductor transistor technologies. However, generating and propagating the necessary spin currents is not low power because large charge currents which dissipate heat are required at device inputs, limiting circuit efficiency. IBM have invested considerably in finding ways to minimise input currents and, in their most promising scheme so far, they have shown that superconductors may help overcome the propagation issue. However, the real breakthrough would be the creation of spin-polarised supercurrents in which there is no dissipation, just as there is no such dissipation for charge current flow within a superconductor. At first sight this appears unlikely because the pairs of electrons (“Cooper pairs”) which carry charge have opposite spins in practically all known superconductors, meaning a supercurrent cannot carry a net spin component. In spite of this, in 2001 a theory was published that predicted that at a carefully engineered superconductor / ferromagnet interface it would in fact be possible to create a source of spin-polarised supercurrents. In 2010 I discovered a way to generate such dissipation-free spin-currents (1) and now my group is investigating the fundamental properties of this new superconducting state (2-5) and the potential to apply it in practical devices. In this talk I will provide an overview of my work on spin-polarised superconductivity and explain how I am developing my group and diversifying my research.