Using electrons to fabricate magnetic nano-circuits

畴壁（DW）存储器是一种类型的固态磁性随机存取存储器，其控制磁畴沿着纳米尺度磁道的运动和位置，即，赛道（RT）存储器。DW的磁矩通过在施加的电流脉冲中从电子转移自旋角动量来驱动。也可以通过沿RT包括缺陷来控制DW的位置，所述缺陷沿着RT将DW保持在电流脉冲之间的适当位置。如果常规RT存储器扩展到三维（3D）RT系统，则它们可以极大地提高其存储密度和连接性。然而，这使得他们的制造和理解DWs的行为非常具有挑战性，由于减少access.The博士项目的主要目的是在原位透射电子显微镜（TEM）纳米芯片上使用聚焦电子束诱导沉积（FEBID）制造三维RT存储器。这将允许纳米打印复杂的3D RT架构，并提供直接访问其局部化学，结构和受控DW运动。通过优化3D RT的组成，几何设计和电流脉冲参数，该项目将有助于解决复杂3D纳米磁性阵列中DW运动的一致性，功率效率控制的关键问题。学生将专注于使用FEBID制造3D RT存储器，并在TEM中表征其化学，结构和磁性。特别是，重点将放在如何焦耳加热/退火影响的饱和磁化强度和畴壁运动通过FEBID结构。博士生还将优化磁成像技术，用于3D RT存储器内动态磁性的实时成像。

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.