Micromagnetic Simulation of Domain Structure Transition in Ferromagnetic Nanospheres under Zero External Field
In this work, we investigated the domain structure transition in ferromagnetic nanospheres at the ground-state conditions under zero external magnetic field by micromagnetic simulation. Four basic ferromagnetic materials, nickel (Ni), permalloy (Py), iron (Fe), and cobalt (Co), with variation in...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Universitas Indonesia
2021-07-01
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| Series: | International Journal of Technology |
| Subjects: | |
| Online Access: | https://ijtech.eng.ui.ac.id/article/view/4278 |
| Summary: | In
this work, we investigated the domain structure transition in ferromagnetic
nanospheres at the ground-state conditions under zero external magnetic field
by micromagnetic simulation. Four basic ferromagnetic materials, nickel (Ni),
permalloy (Py), iron (Fe), and cobalt (Co), with variation in diameters from 20
to 100 nm were modeled in the simulation. It was observed that a transition of
domain structure occurs from a single-domain to a multi-domain structure at a
specific diameter based on the magnetization energy profile. Interestingly, a
vortex–core orientation in the multi-domain regime was related to the
magnetocrystalline axis of the material, which first aligns with the hard-axis
direction, and then changes to the easy-axis direction for low-anisotropy
materials (Ni, Py, and Fe). In contrast, only hard-axis orientation exists for
high-anisotropy materials (Co). Furthermore, it is also observed that the
transition of domain structure was related to the critical diameter. Below the
critical diameter, a single-domain structure is exhibited in which the
demagnetization energy was larger than the exchange energy. A multi-domain
structure emerged above the critical diameter where the exchange energy was
larger than the demagnetization energy. The comparable values of critical
diameter were also calculated based on the Kittel and Brown equations. The
results of the critical diameter from the micromagnetic simulation agreed with
the theoretical calculations. Therefore, an interpretation of these
magnetization dynamics is an important step in the material selection for
granular magnetic-based storage. |
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| ISSN: | 2086-9614 2087-2100 |