Using electrons to fabricate magnetic nano-circuits

点击翻译按钮获取中文摘要

Domain wall (DW) memory is a type of solid-state magnetic random-access memory that controls the motion and position of magnetic domains along a nano-scale magnetic track, i.e., racetrack (RT) memory. The magnetic moments of DWs are driven by transferring spin angular momentum from electrons in an applied current pulse. The position of the DWs can also be controlled by including defects along the RT that hold the DWs in place between current pulses. Conventional RT memories can vastly improve their storage density and connectivity if they expand into three-dimensional (3D) RT systems. However, this makes their fabrication and understanding the behaviour of DWs very challenging due to reduced access.The main aim of this PhD project is to fabricate 3D RT memories on in-situ transmission electron microscopy (TEM) Nano-chips using focused electron beam induced deposition (FEBID). This will allow nano-printing of complex 3D RT architectures and provide direct access to their localised chemistry, structure and controlled DW motion. Through optimising the composition, geometrical design and current pulse parameters of the 3D RTs the project will help address the key issue of consistent, power-efficient control of DWs motion in complex 3D nanomagnetic arrays.The student will focus on fabricating 3D RT memories using FEBID and characterising their chemical, structural and magnetic properties within the TEM. In particular, focus will be placed on how joule heating / annealing affects the saturation magnetisation and domain wall motion through the FEBID structures. The PhD student will also optimise the magnetic imaging techniques for live imaging of dynamic magnetism within the 3D RT memories.