Micromagnetic Simulation of Domain Structure Transition in Ferromagnetic Nanospheres under Zero External Field

International Journal of Technology

卷:12

Candra Kurniawan¹  Dong-Hyun Kim²  Agus Tri Widodo³  Dede Djuhana³ 

[1] 1.Department of Physics, Faculty Mathematics and Natural Science (FMIPA), Universitas Indonesia, Kampus UI Depok, Depok 16424, Indonesia 2. Research Center for Physics, Indonesian Institute of Scien;

[2] Department of Physics, Chungbuk National University, Cheongju 28644, South Korea;

[3] Department of Physics, Faculty Mathematics and Natural Science (FMIPA), Universitas Indonesia, Kampus UI Depok, Depok 16424, Indonesia;

关键词: critical diameter;    domain structure;    micromagnetic;    multi-domain;    single domain;   

DOI  :  10.14716/ijtech.v12i3.4278

来源: DOAJ

【 摘 要 】

Inthis work, we investigated the domain structure transition in ferromagneticnanospheres at the ground-state conditions under zero external magnetic fieldby micromagnetic simulation. Four basic ferromagnetic materials, nickel (Ni),permalloy (Py), iron (Fe), and cobalt (Co), with variation in diameters from 20to 100 nm were modeled in the simulation. It was observed that a transition ofdomain structure occurs from a single-domain to a multi-domain structure at aspecific diameter based on the magnetization energy profile. Interestingly, avortex–core orientation in the multi-domain regime was related to themagnetocrystalline axis of the material, which first aligns with the hard-axisdirection, and then changes to the easy-axis direction for low-anisotropymaterials (Ni, Py, and Fe). In contrast, only hard-axis orientation exists forhigh-anisotropy materials (Co). Furthermore, it is also observed that thetransition of domain structure was related to the critical diameter. Below thecritical diameter, a single-domain structure is exhibited in which thedemagnetization energy was larger than the exchange energy. A multi-domainstructure emerged above the critical diameter where the exchange energy waslarger than the demagnetization energy. The comparable values of criticaldiameter were also calculated based on the Kittel and Brown equations. Theresults of the critical diameter from the micromagnetic simulation agreed withthe theoretical calculations. Therefore, an interpretation of thesemagnetization dynamics is an important step in the material selection forgranular magnetic-based storage.

【 授权许可】

Unknown