Focused Helium and Neon Ion Beam Modification of High-T C Superconductors and Magnetic Materials

Abstract

The ability of gas field ion sources (GFIS) to produce controllable inert gas ion beams with atomic level precision opens up new applications in nanoscale direct-write material modification. Two areas where this has recently been demonstrated is focused helium ion beam production of high-transition temperature (high-T C) superconductor electronics and magnetic spin transport devices. The enabling advance in the case of superconducting electronics is the ability to use the GFIS to make features on the small length-scale of quantum mechanical tunnel barriers. Because the tunneling probability depends exponentially on distance, tunnel barriers must be less than a few nanometers wide, which is beyond the limits of other nanofabrication techniques such as electron beam lithography. In magnetism, the GFIS has recently been used to generate chemical disordering and modify magnetic properties at the nanoscale. The strongest effect is observed in materials where ion-induced chemical disordering leads to increased saturation magnetization, enabling positive magnetic patterning. In this chapter, we review the latest results and progress in GFIS ion beam modification of (high-T C) superconductors and magnetic materials.