Paper MI-ThP2
Magnetic Dot Polarity Switching Via Current Generated Magnetic Fields

Thursday, October 23, 2008, 6:00 pm, Room Hall D

This paper describes the manipulation of the magnetic alignment of nickel dots using a magnetic field generated by current flowing through an aluminum wire. This architecture has the potential to operate as a memory device offering low power dissipation, high integration density, and room temperature operation. The aluminum wire had dimensions of 250 nm in thickness, 10 µm in width, and 40 µm in length. The nickel dots were formed by electron beam lithography and had a thickness of 100 nm and diameter ranging from 200 nm to 500 nm. The dots were deposited in an array such that some dots lay on the wire and some dots lay nearby. A magnetic field was applied to the ferromagnetic dots by passing current through the aluminum wire. Switching of the dots magnetic polarity was observed using magnetic force microscopy (MFM). MFM cantilever phase and amplitude images were used to identify the reversal of the polarity of the dots. Contrast changes were detected upon reversing the current flow. The fabrication of this device concept is relatively simple. Microscale aluminum wires are patterned with conventional photolithographic techniques while a separate electron beam lithography step is used to pattern nickel dots at variable position across the wire. The nickel dot's magnetic field is oriented in a specific direction after passing electric current through the aluminum wire. On reversal of the current, the dot's magnetic field is oriented in the opposite direction. These directions can be treated as a logic '1' or logic '0'. The orientation of the magnetic dots remains even after switching off the current. This indicates potential operation as a memory device.