Focused ion beam (FIB) microscopy suffers from source shot noise - random variation in the number of incident ions in any fixed dwell time - along with random variation in the number of detected secondary electrons per incident ion. This multiplicity of sources of randomness increases the variance of the measurements and thus worsens the trade-off between incident ion dose and image accuracy. Time-resolved sensing combined with maximum likelihood estimation from the resulting sets of measurements greatly reduces the effect of source shot noise. Through Fisher information analysis and Monte Carlo simulations, the reduction in mean-squared error or reduction in required dose is shown to be by a factor approximately equal to the secondary electron yield. Experiments with a helium ion microscope (HIM) are consistent with the analyses and suggest accuracy improvement for a fixed source dose, or reduced source dose for a desired imaging accuracy, by a factor of about 3.
In situ atomic force microscopy depth-corrected 3-dimensional focused ion beam based time-of-flight secondary ion mass spectroscopy: spatial resolution, surface roughness, oxidation
A Workflow for Correlative in-situ Nano-chip Liquid Cell Transmission Electron Microscopy and Atom Probe Tomography Enabled by Cryogenic Plasma Focused Ion Beam
Fabrication of FeSi and Fe3Si compounds by electron beam induced mixing of [Fe/Si]2 and [Fe3/Si]2 multilayers grown by focused electron beam induced deposition
Improvement of a focused ion beam fabricated diamond pillar for scanning ensemble nitrogen-vacancy magnetometry probe using an ultrapure diamond
School of Materials Science, Japan Advanced Institute of Science and Technology（日本科学技术高级学院材料科学学院）；National Institute of Advanced Industrial Science and Technology (AIST)（国立产业技术综合研究所）
Helium Ion Microscopy for Reduced Spin Orbit Torque Switching Currents
自旋轨道转矩驱动开关是一种有利的方式来操纵纳米磁性物体的存储器和无线通信设备。从一种磁状态切换到另一种磁状态所需的临界电流取决于所用材料的几何形状和固有特性，这些特性很难局部控制。在这里，我们展示了如何聚焦氦离子束照射可以调制局部磁各向异性的Co薄膜在微观尺度上。使用异常霍尔效应的实时原位表征显示了辐射下的磁各向异性的数量级减少，并使用此，多电平开关被证明。其结果是，自旋开关电流密度，低至800 kA cm $^{-2}$，可以实现在膜的预定区域，而不需要光刻。空间上改变临界电流的能力不仅对存储元件有影响，而且对神经形态和概率计算也有影响。
