Switching mechanisms and remanent states for nanoscale slotted Co circular elements studied by electron holography

The effect of size and shape on the remanent states and switching behavior for slotted Co disks and rings has been determined using off-axis electron holography. Both shapes have very stable and well-defined remanent states, unlike complete disks and rings with the same dimensions. Slotted disks have vortex states during switching between two single domain states, whereas slotted rings usually show rapid switching without vortex formation. The switching field range of a slotted ring, typically ∼40 Oe, is much smaller than for a complete ring, and is not dependent on the open slot angle or outer diameter. Because of the small leakage field, interelement interactions should be very small for slotted rings with small slot angles, making the shape attractive for high-density data storage applications.