Authors:	Lozhkina, Olga
Title:	Domain wall propagation in soft magnetic wires with periodical width modulation
Online publication date:	11-Sep-2023
Year of first publication:	2023
Language:	english
Abstract:	The relentless pursuit of shrinking computation devices, enhancing their power, reducing energy consumption, and eliminating excessive heat has brought magnetic sensors and spintronics into the spotlight in recent years. These simple, small, and robust magnetic sensors offer high sensitivity, often accompanied by non-volatility and non-contact operation. By incorporating spin as an additional degree of freedom in computation, integration density and computation speed can be improved compared to conventional systems. Permalloy (Ni81Fe19) is a commonly used material for magnetic sensors due to its low coercivity and negligible magnetostriction. The deposition conditions of permalloy thin film using magnetron sputtering were investigated to achieve films with the lowest possible coercivity and controlled anisotropy for magnetoresistive sensor applications. Varying the inert gas pressure, deposition power and magnetic fields during growth is used to obtain films with controlled anisotropy and low coercivity. A robust method for characterising the intrinsic magnetic anisotropy of the films is developed and the possibility of suppressing magnetic anisotropy by introducing a rotating magnetic field during sputtering is demonstrated. Among other spintronic concepts the study of domain wall propagation in magnetically soft nanowires is gaining attention for the potential use in logic, memory and sensor devices. Using micromagnetic simulations, it is shown that a periodic modulation of the wire width can completely eliminate the Walker breakdown of a field-driven domain wall for a certain field range, while preserving the domain wall spin structure over the entire operating field range of a device. The effectiveness of this wire width modulation depends on the width and thickness of the wire, with smaller wires showing the greatest benefit in extending the field operation window. The simulation of crossing magnetic wires also shows the importance of suppressing the Walker breakdown. The experimental results support the findings that the efficiency of the Walker breakdown suppression´depends on the geometry of the magnetic wire, with the domain wall velocity as a function of applied field strength showing a significantly lower slope in modulated wires, in contrast to the sharp peaks associated with Walker breakdown in straight magnetic wires.
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-9381
URN:	urn:nbn:de:hebis:77-openscience-5ffdffba-bfe8-4e3a-a4e6-69f14db4df816
Version:	Original work
Publication type:	Dissertation
License:	In Copyright
Information on rights of use:	http://rightsstatements.org/vocab/InC/1.0/
Extent:	xviii, 110 Blätter ; Illustrationen, Diagramme
Appears in collections:	JGU-Publikationen