STUDY OF MAGNETIC-PROPERTIES OF MAGNETIC FORCE MICROSCOPY PROBES USING MICRONSCALE CURRENT RINGS

Metal rings with inner diameters of 1 and 5 mu m, fabricated using ele ctron-beam lithography, were used to calibrate magnetic force microsco py (MFM). A MFM tip's effective magnetic charge, q, and effective magn etic moment along the tip long axis, m(z), can be determined by the cu rrent flowing in the ring. The magnetic moments in the directions tran sverse to the tip's long axis were estimated by a straight current wir e. It was found that for a silicon tip coated with 65 nm thick cobalt on the side, q = 2.8 x 10(-6) emu/cm, m(z) = 3.8 x 10(-9) emu, and m(x ) = m(y) = 10(-13) emu, which are negligible compared with m(z). Furth ermore, the tip's sensitivity to the second derivative of the magnetic field was found to be about 0.1 Oe/nm(2). (C) 1997 American Institute of Physics.