Applied Physics

Consistent at Tap

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Science  04 Jan 2002:
Vol. 295, Issue 5552, pp. 15-17
DOI: 10.1126/science.295.5552.15d

Several proposals have been put forward for ultrahigh density memories in which reading or writing operations involve the use of an atomic force microscope (AFM), which can map surface topography with high resolution when operated in the “tapping mode.” One drawback, however, is that the tip tends to take a somewhat chaotic path during imaging, and many scans need to be averaged to achieve consistent resolution. Fein et al. evaluate the ability of an AFM with an all-metal conducting tip operating in tapping mode to inject current pulses into a conducting gold substrate. Currents pulses up to 10 microamperes per square centimeter can be injected each time the tip comes into contact with the surface, which is sufficiently high to modify the surface by heating or to reverse the magnetization in a ferromagnetic region. These pulses were almost identical in shape even when tapping at the same position. Such reproducibility should decrease the need for averaging and thus boost the bit rate of associated processes. — ISO

Appl. Phys. Lett.79, 3935 (2001).

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