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Abstract: A software 2D micromagnetic simulator (OOMMF - Object Oriented Micromagnetic Framework) was used to simulate magnetization curves and show the evolution of magnetic domains for a Permalloy (Ni80Fe20)-based thin film. A comparison between different Simulmag and OOMMF software solutions is made. This paper is intended to serve as a guide in the software simulation of magnetization dynamics in micrometer sized structures with OOMMF while also reaching some essential conclusions regarding the development of sensing applications using associated magnetic effects. Simulation results are joined and confirmed by some experimental data.
Key words: thin films, hysteresis loop, micromagnetic simulation, magnetic domains, Landau-Lifshitz-Gilbert (LLG) equation.
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1.Introduction
Magnetization dynamics of thin films is a crucial research topic necessary in the development of novel technologies including sensors, oscillators, various types of magnetic memories like Spin-Transfer Torque MRAM or Spin Orbit Torque MRAM [5] and other applications that have a focus on spintronics. In this regard, the software simulation of micromagnetic structures is a vital step. Although there are plenty of free software that simulate single domain structures, there are significantly less choices for multi-domain structures and they typically come at a great cost or require specific hardware. In terms of free solutions, the Object Oriented Micro Magnetic Framework (OOMMF) project developed by Information Technology Group inside National Institute of Standards became a standard solution for micromagnetic simulations due its performance, stability and portability. The object oriented micromagnetic framework (OOMMF) has been developed by Mike Donahue and Don Porter in the National Institute of Standard and Technology. The program is based on C++ with Tcl/Tk.
2. Theoretical Aspects
Various technological applications are explored by phenomena like the planar Hall effect (PHE), anisotropic magnetoresistance effect (AMR) giant magnetoresistance effect (GMR) or tunneling magnetoresistance effect (TMR) that magnetic thin films and nanostructured magnetic systems are exhibiting.
In practice it was observed that if a magnetic material is introduced in magnetic field of a certain direction and whose intensity is gradually and slowly increasing, the resultant magnetization progressively increases until it is reaching the saturation value [5].
Systems with hysteresis behaviour are nonlinear, and can be mathematically challenging to model. Some phenomenological models like the Preisach model [1] or the Jiles-Atherton model are used to describe at...