APPLIED PHYSICS LETTERS, vol.109, no.18, 2016 (Journal Indexed in SCI)
In this report, we present a three dimensional (3D) imaging of magnetic field vector (B) over right arrow (x,y,z) emanating from the magnetic material surfaces using a scanning Hall probe microscopy (3D-SHPM) down to a 700 nm spatial resolution. The Hall probe is used to measure B-z(x,y) on the specimen surface at different heights with the step size of Delta z = 250 nm, as we move away from the surface in z direction, until the field decays to zero. These set of images are then used to get partial derivative B-z(x,y)/partial derivative x and partial derivative B-z(x,y)/partial derivative y at different z by numerical differentiation. Using the Maxwell's equations in the source free region, B-x(x,y) and B-y(x,y) can be calculated by integrating partial derivative B-z(x,y)/partial derivative x and partial derivative B-z(x,y)/partial derivative y in the z direction. Alternatively, the gradients can also be measured in the Hall gradiometer configuration directly. The operation of the 3D-SHPM is demonstrated by imaging B-x(x,y), B-y(x,y) and B-z(x,y) on a hard disk specimen at a 700 nm resolution, using both of these methods at 77 K. The system is capable of operating from 300 K down to 4 K range. Published by AIP Publishing.