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Kurniawan Candra,Djuhana Dede,Soegijono Bambang,Kim Dong-Hyun 한국물리학회 2021 Current Applied Physics Vol.27 No.-
We report our micromagnetic simulations based on Landau-Lifshitz-Gilbert (LLG) equation for CoFeB nanowire which was exposed by sub-nanosecond magnetic pulse with varied pulse width between 100 and 1000 ps. It is found that the Walker Breakdown field (HWB) shifted as the field pulse duration decreased and reached at the highest value in case of 100 ps pulse width, then decreased steeply with respect to the pulse width up to 400 ps. HWB values are not significantly dependent for pulses longer than 500 ps. It is observed that, below the HWB, the exchange energy is larger than the demagnetization energy in the wider nanowire. By energy density analysis, it is understood that the increase of HWB values in the cases of narrower pulse width was to compensate the energy needed to move the DW.
Dede Djuhana,Candra Kurniawan,김동현 한국물리학회 2018 Current Applied Physics Vol.18 No.2
The complete understanding of domain wall (DW) dynamics is important in the design of future spintronic devices. The characteristics of faster time-scale and lower current amplitude to move DW along nanowire are crucial in fabrication upgrade. In this study, we have investigated depinning behavior of magnetic domain wall triggered by nanosecond current pulse in notched Permalloy nanowires by means of micromagnetic simulation. We introduced double-triangular notch as the constrictions in the nanowire. The non-adiabaticity of the spin-transfer-torque is considered in simulation by varying the non-adiabatic constant (β) value. We observed that the depinning current density (Jd) was not significantly affected by β for notch size (s) < 50 nm. Interestingly, we found that the depinning time (td) for β ≥ 0.04 was slightly constant for all the cases with s > 70 nm, where the DW structure was kept to be a transverse structure during the depinning process. The broadly applicable depinning behavior is considered to contribute to the development of high-speed memory storage devices based on magnetic domain wall.
Lin Huang,Iwan Sugihartono,Djati Handoko,양동석,Candra Kurniawan,Erfan Handoko,김동현 한국물리학회 2019 Current Applied Physics Vol.19 No.3
We have investigated the correlation between structural and magnetic properties of M-type BaFe12O19 thin films (∼1.4 μm) with Co-Ti (magnetic/non-magnetic) and Co-Ni(magnetic/magnetic) substitution, as BaFe12- 2xCoxTixO19 and BaFe12-2xCoxNixO19 (0≤x≤1). With structural properties sensitively related to the magnetic properties, where ferro-ferri phase transition is involved, it has been found that magnetic properties can be substantially controlled by substitution concentration.
Wahyu Widanarto,Mukhtar Effendi,Sib Krishna Ghoshal,Candra Kurniawan,Erfan Handoko,Mudrik Alaydrus 한국물리학회 2020 Current Applied Physics Vol.20 No.5
A series of bio-silica incorporated barium-ferrite-composites with the composition of (x)Bio-SiO2:(80-x)γ-Fe2O3: (20)BaO, where x = 0, 1, 2, and 3 wt% were prepared using the modified solid-state reaction method. The influence of different bio-silica (extricated from sintered rice husk) contents on the surface morphologies, structures, and magnetic characteristics of these composites were assessed. The relative complex permittivity and permeability were resolved using the Nicholson-Ross-Weir strategy in the frequency range of 8–13 GHz. Meanwhile, the reflection loss was estimated through the transmission/reflection line theory to assess the MW absorption properties of the composites. Incorporation of the bio-silica in the barium ferrite composites generated a new hexagonal phase (Ba3Fe32O51) and a tetragonal phase (BaFeSi4O10) which led to a decrease in the saturation magnetization and significant shift in the MW frequency absorption peak positions.