Micromagnetic Investigation of Magnetic Domain Wall Depinning Dynamics by Symmetrical Triangular Notch Geometries in Perpendicular Magnetization CoFeB Nanowire
Candra Kurniawan 1, 2 a) and Dede Djuhana 1, b)

1Departement of Physics, Faculty of Mathematics and Natural Sciences, Universitas Indonesia (UI), Kampus Baru UI Depok 16424, Indonesia.

2Research Center for Advanced Materials, National Research and Innovation Agency (BRIN), KST BJ Habibie Office Area, Tangerang Selatan 15314, Indonesia.

Abstract

To optimally control the DW in the nanowire, there are some focuses on the utilization of geometrical notch as an artificial pinning potential. Most of the studies were intended to explain the dynamics of DW structure when passes or move out from the notch. However, there is still a lack of discussion about the geometrical structure of notch in the nanowires. Our previous studies explained the effect of notch length and dept to the DW depinning behavior by electrical current and magnetic field pulse in in-plane magnetization Permalloy material. In this work, the dynamics of domain wall depinning by double triangular notch in the perpendicular magnetization CoFeB nanowire was investigated using micromagnetic simulation from the initial ground-state condition. The micromagnetic model of material was mimicking the CoFeB stripe-shape nanowire with a perfect single crystalline structure. The simulation process was performed by relaxing the initial Bloch-type wall for 1 ns. Then the electrical current pulse was injected to the wire on the +x-direction for 1 ns of pulse length. The DW depinning condition determined by the edge of DW leave out the notch area, which was relate to the artificial pinning potential in the nanowire made by the notch. The micromagnetic results showed that the notch depth (d) variation was linearly increasing the value of the depinning current density, Jd. However, the Jd value was significantly increasing on the larger size of d, particularly on d > 20 nm. Therefore, this work explained that the small difference size of a particular notch design should be considered to achieve better control in the DW based devices.

Keywords: CoFeB- depinning- domain wall- micromagnetics- nanowire

Topic: Magnetic materials