Is there any material that a magnetic flux will not pass through?
The B-field goes to zero fairly quickly inside a superconductor.
Any ferromagnetic material will block and redirect the field. This is the basis of magnetic shielding in electronic devices.
As noted by previous respondants, a ferromagnetic material will collect all of the flux lines to itself, and so will screen things that are beyond it. This is really the opposite of not passing through. A good diamagnet will screen magnetic flux, preventing the flux from penetrating the material. A superconductor in its type 1 regime will work, but at room temperature you can get very good results with a material called mu metal.
