Using STEM-DPC with a Conventional ADF Detector to Explore FIB Patterned Artificial Spin Ice Structures in Permalloy
(2023)- Abstract
- We find ourselves in the midst of a remarkable technological revolution, with rapid advancements in fields such as artificial intelligence, robotics and information technology. Consequently, there is a pressing need for low-power technologies that are not reliant on continuous power supply. The field of spintronics aims to resolve this by coupling electric and magnetic properties. To pave the way for this new technology, it is imperative to deepen our understanding of how magnetism acts at the nanoscale by exploring the behaviour of magnetic nanostructures. Fortunately, with the advancements made in nanofabrication and characterization equipment over the past decades, our ability to study magnetism all the way down to the nanoscale is... (More)
- We find ourselves in the midst of a remarkable technological revolution, with rapid advancements in fields such as artificial intelligence, robotics and information technology. Consequently, there is a pressing need for low-power technologies that are not reliant on continuous power supply. The field of spintronics aims to resolve this by coupling electric and magnetic properties. To pave the way for this new technology, it is imperative to deepen our understanding of how magnetism acts at the nanoscale by exploring the behaviour of magnetic nanostructures. Fortunately, with the advancements made in nanofabrication and characterization equipment over the past decades, our ability to study magnetism all the way down to the nanoscale is ever-increasing. Among the myriad of fascinating nanosized magnetic systems, is artificial spin ice (ASI). ASIs are geometrically frustrated systems composed of coupled nanomagnets arranged in a two-dimensional lattice and have since their discovery in 2006 been extensively studied as model systems to explore magnetic frustration. In the last decade, ASIs have also shown great promise for use in novel and efficient ways to store data and for alternative computing methods like reservoir computing. To accelerate our understanding of ASI systems, efficient and accessible characterization methods are needed. Scanning transmission electron microscopy (STEM) is a well-established technique predominantly used to study nanoscale structures with Ångstrøm resolution, map chemical composition and map crystallographic orientations within materials. However, by turning off the objective lens (OL) of the microscope, internal magnetic fields in materials can be imaged by utilizing the Lorentz force, which leads to a deflection of the electron beam that is detectable on any standard STEM detector. This technique is called STEM - differential phase contrast (DPC). By combining STEM-DPC with a weakly excited OL and tilting the sample, it is even possible to image the switching of ferromagnetic domains in materials down to the nanoscale. In this work, we have successfully fabricated a wide range of ASI systems composed of islands as small as 225nmx75nm, using a focused ion beam (FIB). The structures were characterized with two distinct STEM-DPC techniques using a conventional annular dark field (ADF) detector. The fabrication and characterization techniques showed exceptionally good results, indicating that the methodology is indeed well-suited for fast prototyping and characterization of ASIs, and can even be combined with structural and chemical analysis in the TEM. Due to continuous advancements in aberration correction and STEM detectors, it is believed that this can become a valuable tool in the development of novel, low-power spintronic devices. (Less)
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https://lup.lub.lu.se/record/378f016a-064c-40df-8f23-e746bc2474c3
- author
- Soland, Hedda Christine LU
- supervisor
- publishing date
- 2023
- type
- Thesis
- publication status
- published
- keywords
- LM-STEM-DPC, Magnetic Imaging, Artificial Spin Ice, FIB, Lorentz Microscopy, magnetism in nanostructures
- language
- English
- LU publication?
- no
- id
- 378f016a-064c-40df-8f23-e746bc2474c3
- date added to LUP
- 2023-11-12 02:49:51
- date last changed
- 2023-11-22 09:54:43
@misc{378f016a-064c-40df-8f23-e746bc2474c3,
abstract = {{We find ourselves in the midst of a remarkable technological revolution, with rapid advancements in fields such as artificial intelligence, robotics and information technology. Consequently, there is a pressing need for low-power technologies that are not reliant on continuous power supply. The field of spintronics aims to resolve this by coupling electric and magnetic properties. To pave the way for this new technology, it is imperative to deepen our understanding of how magnetism acts at the nanoscale by exploring the behaviour of magnetic nanostructures. Fortunately, with the advancements made in nanofabrication and characterization equipment over the past decades, our ability to study magnetism all the way down to the nanoscale is ever-increasing. Among the myriad of fascinating nanosized magnetic systems, is artificial spin ice (ASI). ASIs are geometrically frustrated systems composed of coupled nanomagnets arranged in a two-dimensional lattice and have since their discovery in 2006 been extensively studied as model systems to explore magnetic frustration. In the last decade, ASIs have also shown great promise for use in novel and efficient ways to store data and for alternative computing methods like reservoir computing. To accelerate our understanding of ASI systems, efficient and accessible characterization methods are needed. Scanning transmission electron microscopy (STEM) is a well-established technique predominantly used to study nanoscale structures with Ångstrøm resolution, map chemical composition and map crystallographic orientations within materials. However, by turning off the objective lens (OL) of the microscope, internal magnetic fields in materials can be imaged by utilizing the Lorentz force, which leads to a deflection of the electron beam that is detectable on any standard STEM detector. This technique is called STEM - differential phase contrast (DPC). By combining STEM-DPC with a weakly excited OL and tilting the sample, it is even possible to image the switching of ferromagnetic domains in materials down to the nanoscale. In this work, we have successfully fabricated a wide range of ASI systems composed of islands as small as 225nmx75nm, using a focused ion beam (FIB). The structures were characterized with two distinct STEM-DPC techniques using a conventional annular dark field (ADF) detector. The fabrication and characterization techniques showed exceptionally good results, indicating that the methodology is indeed well-suited for fast prototyping and characterization of ASIs, and can even be combined with structural and chemical analysis in the TEM. Due to continuous advancements in aberration correction and STEM detectors, it is believed that this can become a valuable tool in the development of novel, low-power spintronic devices.}},
author = {{Soland, Hedda Christine}},
keywords = {{LM-STEM-DPC; Magnetic Imaging; Artificial Spin Ice; FIB; Lorentz Microscopy; magnetism in nanostructures}},
language = {{eng}},
title = {{Using STEM-DPC with a Conventional ADF Detector to Explore FIB Patterned Artificial Spin Ice Structures in Permalloy}},
url = {{https://lup.lub.lu.se/search/files/164804534/mastersthesis_HCS_23.pdf}},
year = {{2023}},
}