Authors:	Meer, Hendrik
Advisor:	Kläui, Mathias
Title:	Antiferromagnetic insulatronics: control and manipulation of magnetic domains
Online publication date:	13-Nov-2023
Year of first publication:	2023
Language:	english
Abstract:	The control and manipulation of the antiferromagnetic order in insulating magnetic thin films is of paramount importance for advancing the development of possible high-speed, energy-efficient spintronic devices. The field of antiferromagnetic insulatronics has great potential to overcome the limitations of conventional electronic devices due to the inherent advantages of insulating antiferromagnets. These materials exhibit intrinsic frequencies in the THz range, surpassing ferromagnets, and possess the ability to transport information through pure spin currents. Thus, allowing for the mitigation of Joule heating issues commonly encountered in current devices. However, the absence of a net magnetic moment poses a significant challenge for writing the antiferromagnetic order, thereby hindering further exploration of their properties and their practical implementation as active elements. Therefore, the aim of this thesis is to investigate and establish mechanisms to control and manipulate the magnetic order in insulating antiferromagnets. Here, we investigate three different mechanisms to manipulate the domain structure in antiferromagnetic NiO and CoO thin films. First, we explore current-induced switching in bilayers of heavy metals and insulating antiferromagnets. Using birefringence imaging, we optically study the current-induced changes in the domain structure. By examining different device and pulse geometries, we identify a heat- and strain-based switching mechanism, thereby resolving previously conflicting switching interpretations based on spin-orbit torque mechanisms. Second, we investigate the influence of the patterning geometry on a device. Although shape anisotropy, as it is established in ferromagnets due to dipolar interactions, is not expected, theoretical studies suggest that analogous effects may occur in antiferromagnets due to magnetoelastic coupling. We use the X-ray magnetic linear dichroism effect in photoemission electron microscopy to reveal a strain-induced antiferromagnetic shape anisotropy. Thereby, we enable the tailoring of the antiferromagnetic ground state of a device. Third, we investigate a contactless switching mechanism. By irradiating our domain structures with pulse trains of laser light with different polarizations and fluences, we observe the creation of antiferromagnetic 180 ° domain walls and domains. The underlying mechanism is based on laser-induced heating and limited by the inherent strain in our samples. In summary, this work aims to address the challenges associated with the control and manipulation of antiferromagnetic order in insulating thin films. By exploring current-induced switching, antiferromagnetic shape anisotropy, and laser-induced domain creation, our research contributes to expanding the toolbox of antiferromagnetic insulatronics and reveals the critical role of strain and heat. These findings provide a foundation for the future development of antiferromagnets as active elements in spintronic devices and further exploration of the fascinating properties of insulating antiferromagnets.
DDC:	530 Physik 530 Physics
Institution:	Johannes Gutenberg-Universität Mainz
Department:	FB 08 Physik, Mathematik u. Informatik
Place:	Mainz
ROR:	https://ror.org/023b0x485
DOI:	http://doi.org/10.25358/openscience-9644
URN:	urn:nbn:de:hebis:77-openscience-28fdec2a-3d31-44f2-a865-f5bff3996bb53
Version:	Original work
Publication type:	Dissertation
License:	In Copyright
Information on rights of use:	http://rightsstatements.org/vocab/InC/1.0/
Extent:	ix, 162 Seiten ; Illustrationen, Diagramme
Appears in collections:	JGU-Publikationen