MAGNETIC FORCE MICROSCOPE USING A DIRECT RESONANCE FREQUENCY SENSOR OPERATING IN AIR

A magnetic force microscope (MFM) using a direct resonance frequency sensor which can be operated in the air has been developed. This instrument is simple and easy to handle because a vacuum system is not needed. The cantilever is used as a resonator in the oscillator, and its oscillating frequency is detected by a frequency modulation (FM) demodulator. A phase locked loop (PLL) FM demodulator is used which is less affected by noise. The cantilever is fabricated by Si microprocessing and its tip formed by precise focused ion beam (FIB) milling. MFM images demonstrate that this instrument has a performance almost the same as that which can be achieved in vacuum. It also has a scanning speed which is approximately 10 times as fast as that of an instrument using conventional slope detection techniques, and its signal-to-noise ratio is comparable to that of conventional systems.