The highest possible spin polarization is proposed for half-metals. In these materials the current is carried by the electrons that have the same spin. This arises due to the fact that half-metals exhibit a semiconducting like energy gap for the spin down electrons at the Fermi energy, which forbids the electrons having spins with down configuration. There are certain methods of detecting spin polarization like photo emission, tunneling spectroscopy and point contact Andreev reflection (PCAR) spectroscopy etc.

Dear Rajib Biswas ,

Thanks for your Valuable reply ,It gives me a point to consider