Domain Wall Injection Behavior on Wide Wire Using a Moke Microscopy
許登翔1*, 洪韻1, 蘇俊翰1, 林集揚2, 賴高範1, 吳仲卿1, 洪連輝1
1物理學系, 國立彰化師範大學, 彰化縣, Taiwan
2光電所, 國立彰化師範大學, 彰化縣, Taiwan
* Presenter:許登翔,
In the definition of domain wall (DW) injection, after DW is injected from injection pad by current or magnetic field, the DW will movie continually until stop at any kind of pinning sites, such as notch or local field. Interestingly, in our recently work, we found that the behavior of DW injection will randomly stop at 2μm wire without pinning site, we name it half injection. In order to investigate the half injection, we fabricate samples by e-beam lithography and magnetron sputtering. The injection pad is connected at left side of wire. The wire is designed with and without 1μm depth of notch. The injection pad diameter, wire width and permalloy(Py) thin film thickness are 20 μm, 2μm and 20 nm, respectively. For the notch influence determine, the notches is located at 10 μm, 27μm and 47μm from the pad. The measurement employ magnetic optical Kerr effect (MOKE) microscope. Through analysis magnetic images from MOKE microscope, the half injection probability of device without notch is 23%. The half injection probability of wire with notch which locate at at 10 μm, 27μm and 47μm from the pad are around 50 %. That indicates the half injection is influenced by notch. The half injection behavior is caused by thermal fluctuation of DW configuration and local moments near notch. We find nice reproducibility on different sets of device. The reproducibility indicates that the inhomogeneous elements distribution of Py films have weak influence for half injection. For determining the influence of surface, we will fabricate device by sputtering and molecular beam epitaxy (MBE). Then confirm the surface has less influence on half injection.

Keywords: Domain wall motion, NiFe, MOKE microscope, Magnetic material