Multi-modal electron microscopy of 3D racetrack memory

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Modern society is becoming increasingly reliant on digital data, yet most data is stored on magnetic hard disk drives that consume large amounts of energy and are limited in reliability. As data centres and volumes of servers grow it is becoming necessary to explore more efficient future digital storage technologies.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 aim of this project is to use advanced electron microscopy techniques to construct 3D RT memories that provide direct, nano-scale analysis of their chemistry, structure and DW motion under operando conditions (current pulsing and heating). This will allow effective engineering of their operation, taking the functional performance of 3D RTs into a brand-new realm of understanding. Through optimising the composition, geometrical design and current pulse parameters of the 3D RTs we can address the key issue of consistent, power-efficient control of DWs motion in complex 3D nanomagnetic arrays.The results will not only lead to high impact publications and conference presentations, but also provide a wealth of information for expanding the field of spintronics into advanced nanomagnetic systems with complex 3D geometries.