抄録
Gamma'-Fe4N is the ferromagnetic material with high Curie temperature and relatively high electrical conductivity. First principle calculation showed that the ganma'-Fe4N was a half-metal by 100% spin polarized conduction electrons with minority spins. So we expected large tunneling magneto-resistance effect in the Fe4N/MgO/Fe4N junctions. Gamma'-Fe4N was prepared by sintering Fe3O4 nanoparticles in the atmosphere of NH3/H2 gas mixture at 673 K. Then MgO was added to the gamma'-Fe4N powder and sintered at about 473 K in pure Ar gas. Magneto-resistance was measured by 4-terminals method for x=0-0.8 samples of (MgO)x(Fe4N)1-x, and magneto-resistance ratios of -1.2~-1 % were observed for x=0.3~0.6 samples at 300K. It is the first observation oftunneling magneto-resistance effect for gamma'-Fe4N granular system.
