| 摘要 |
Magnetic structures of a sample (46) are imaged by measuring Lorentz force-induced deflection of the tip (40) of a scanning tunneling microscope. While scanning the sample (46), an a.c. voltage signal at a first predetermined frequency equal to the resonance frequency of the tip (40) is applied to the tip (40) for generating a current between the tip (40) and the surface (44) of the sample (46) for causing the tip (40) to undergo vibratory motion relative to the sample (46). The tip (40) motion, indicative of the presence of a magnetic field, is optically detected. In an alternative embodiment for providing improved resolution the tip (40) is made to undergo motion at a second predetermined frequency in a direction parallel to the longitudinal axis of the tip (40) and normal to the surface (44) of the sample (46). The tip (40) motion is optically detected at the sum or difference frequency of the first and second predetermined frequencies for providing improved lateral resolution of the magnetic field measurements using a scanning tunneling microscope. In the alternative embodiment the sum or difference frequency, which ever is detected, is made equal to the resonance frequency of the tip (40). The magnetic field measurement and tip (40) position are provided to a computer (68) which, in turn, provides an output signal to a device (72) for providing a graphical representation of the magnetic field at different positions on the surface (44) of the sample (46). |
