Full text loading...
The magnetic domain wall displacement in electric field. (a) Schematic representation of the geometry of the experiment and the configurations of the electric field and magnetization. The electric field (the field lines are shown by the dashed lines) is formed in the dielectric medium of the sample between the tip (1) and the copper foil (2), which plays the role of the grounding electrode. The maximum field strength (about 800 kV/cm) is reached in the iron garnet film (3) near the tip at the voltage of 500 V applied; it decreases rapidly in the bulk of substrate (4) and does not exceed 500 V/cm near the grounding electrode (2). The absence of the leakage currents is controlled with the milliamperemeter (mA). The incident light (denoted with wavy arrows) is along the normal to the surface. The objective lens (5) is placed behind the pinhole in the foil (2). In the magnetic film (3) the domains and domain wall (DW) are schematically shown. (b) Magneto-optical images of domain walls at the tip electrode potentials of and superimposed on each other. In the vicinity of tip electrode (1) the segment of domain wall (2) is attracted to the tip at a positive potential of (red) and is repelled by the tip at a negative potential of (blue). The equilibrium position of the domain wall is shown by the dashed line. Three positions of the wall in selected area (from left to right: , 0, and ) are shown in the inset. In (210) films the domain walls have the tendency to orient along the crystallographic direction. Sample 7 from Table I was used.
Dynamic measurements of the domain wall displacement in iron garnet films under a steplike voltage pulse of (duration of 300 ns and rise time of 20 ns). Sample 6 from Table I was used. (a) The initial micromagnetic configuration: (1) is the tip electrode and (2) is the stripe domain head. Photos of selected area show the consecutive stripe domain head positions: before electric pulse (0 ns) and instantaneous position of the domain wall moving in electric field pulse (50 ns from the start of the pulse), at ultimate equilibrium position in electric field (100 ns from the pulse start). The broadening of stripe domain head images is a characteristic feature of (210) films caused by the tilt of the easy axis from the normal to the film surface. (b) The dots on graphs show the domain wall displacement vs time for pulses with voltages of 200 V (black squares), 300 V (red circles), and 400 V (green triangles). The dashed lines are interpolation of the dependences. The linear fit of ascending sections of the curves gives the values of the velocities of , , and for 200, 300, and 400 V, respectively. The large dispersion of experimental points for dynamic dependences in low field (200 V) probably is related to domain wall pinning at the defects.
Parameters of the samples under study and magnetoelectric control effect registration marks. The symbol stands for the thickness of the iron garnet film, is the saturation magnetization, is a period of domain structure, and are angular coordinates of the magnetic easy axis in the coordinate system with the direction normal to the film as the -axis, and and as the -axes for (110) and (210) films, respectively (data adopted from Ref. 15). At the right column the presence/absence of the magnetic domain wall displacement in electric field is indicated.
Article metrics loading...