[Getdp] Magnetic STM tip - possible with GetDP magnetostatics?

[Emanuel Gull]

Hello everybody,

currently I'm trying to simulate a problem with GetDP, but I'm not sure 
if it's possible at all. The problem is as follows:

We're currently trying to manufacture a tip for a scanning tunneling 
microscope that has macroscopic dimensions on one side (i.e. a few mm 
long, 0.25 mm thick) and microscopic dimensions on the other side 
(radius of only 50 nm, about 10-20 Angstrom (1-2 nm) away from the sample).

The tip is made out of a cobalt wire, around which we'll wind a small coil.

We want to know if the magnetic field that is produced by the coil at 
the tip of the Co wire is strong enough to reverse the magnetization of 
some small magnetic islands, i.e. we have to compute the field  just 
outside the tip. This has to be in no way accurate (for that we have the 
experiment), we just want some initial guess for the field strength.

Currently the geometry is allright, but the mesh algorithm fails - 1 nm 
on a mm scale is just too small. Therefore my question:

- Is GetDP the right tool to simulate this problem? Can one go over 6 
orders of magnitude in such a simulation?

- Has anything like that ever been done before, and would there be a 
reasonable way to check the result?

Yours sincerly,

Emanuel Gull