Method and apparatus for magnetic force control of a scanning probe

A method of magnetic force control for a scanning probe, comprising the steps of:

• disposing a first magnetic source on said scanning probe, said first magnetic source having a magnetic moment;
• disposing a second magnetic source external to said scanning probe to apply a magnetic field in a direction other than parallel to the orientation of said magnetic moment from said second magnetic source to said first magnetic source so as to produce a torque related to the amplitude of the applied magnetic field acting on said scanning probe;
• and
• controlling the amplitude of said magnetic field to maintain the deflection of said scanning probe constant during scanning by said scanning probe by sensing the deflection of said scanning probe as caused by a surface force during said scanning and applying said magnetic field with an amplitude derived based on the sensed deflection, wherein said applying step comprises applying at least one of a proportional gain and an integral gain to a signal related to the sensed deflection to derive said amplitude of said magnetic field.

A magnetic force control apparatus for a scanning probe, comprising:

• a probe provided with a first magnetic source with said first magnetic source having a magnetic moment;
• a second magnetic source disposed external to said probe to apply a magnetic field to said first magnetic source in a direction other than parallel to the orientation of said magnetic moment so as to produce a torque related to the amplitude of the applied magnetic field acting on said probe;
• and
• control means for controlling the amplitude of said magnetic field applied by said second magnetic source to maintain deflection of said probe constant, comprising means for sensing the deflection of said probe as caused by a surface force, and means for controlling the amplitude of said magnetic field applied by said second magnetic source based on the sensed deflection of said probe, wherein said means for controlling the amplitude of said magnetic field includes at least one of a proportional gain and an integral gain in processing a signal related to the sensed deflection of said probe.