Çok frekanslı akıgeçiş manyetik kuvvet mikroskopisi

In the recent years, progress in atomic force microscopy (AFM) led to the multifrequencyimaging paradigm in which the cantilever-tip ensemble is simultaneouslyexcited by several driving forces of different frequencies. By using multifrequencyexcitation, various interaction forces of different physical origin suchas electronic interactions or chemical interactions can be simultaneously mappedalong with topography. However, a multifrequency magnetic imaging techniquehas not been demonstrated yet. The difficulty in imaging magnetic forces usinga multifrequency technique partly arises from difficulties in modulation of themagnetic tip-sample interaction. In the traditional unmodulated scheme, measurementof magnetic forces and elimination of coupling with other forces is obtainedin a double pass measurement technique where topography and magneticinteractions are rapidly measured in successive scans with different tip-sampleseparations. This measurement scheme may suffer from thermal drifts or topographicalartifacts. In this work, we consider a multifrequency magnetic imagingmethod which uses first resonant flexural mode for topography signal acquisitionand second resonant flexural mode for measuring the magnetic interactionsimultaneously. As in a fluxgate magnetometer, modulation of magnetic momentof nickel particles attached on the apex of AFM tip can be used to modulatethe magnetic forces which are dependent on external DC fields through the nonlinearmagnetic response of the nickel particles. Coupling strength can be variedby changing coil current or setpoint parameters of Magnetic Force Microscopy(MFM) system. Special MFM tips were fabricated by using Focused Ion Beam(FIB) and magnetically characterized for the purpose of multifrequency imaging.In this work, the use of such a nano-flux-gate system for simultaneous topographicand magnetic imaging is experimentally demonstrated. The excitation and detectionscheme can be also used for high sensitivity cantilever magnetometry.