Realization of an ultra-high magnetic field on a nano-scale

In tunnel junctions of which at least one side is a ferromagnet, very large magnetic polarization change ($\approx 0.1 \mu_B$) and splitting of the spin up and spin down Fermi energy ($\approx 0.1 eV$) can be created under steady state finite current conditions (bias voltage $\approx$ 1 volt). This is {\bf much higher} than can be created by the highest magnetic field on earth. We illustrate this with a specific calculation of a recently observed very large Hall effect in the Al side of a Co-I-Al tunnel junction. Other recent experiments that support this idea are discussed.