Current-induced magnetization switching at low current densities in current-perpendicular-to-plane structural Fe₃Si/FeSi₂ artificial lattices

Abstract

Current-perpendicular-to-plane junctions with different cross-sectional areas were fabricated from Fe3Si/FeSi2 artificial lattice films, wherein antiferromagnetic interlayer coupling was induced across the FeSi2 spacer layers, by employing a focused ion beam (FIB) apparatus. Evident hysteresis loops in the electrical resistance for current injection due to current-induced magnetization switching (CIMS) were observed. The average value of critical current densities for inducing CIMS was 2  10 2 A/cm 2 , which is at least three orders of magnitude smaller than values that have ever been reported. This might be because CIMS in our junctions is induced by the destruction of the AF interlayer coupling, which differs from the general mechanism of CIMS.

Temperature-dependent magnetoresistance effects in Fe3Si/FeSi2/Fe3Si trilayered spin valve junctions

“…The shape of the magnetization curve has clear steps that evidently indicate the formation of antiparallel alignment of magnetizations owing to the difference in the coercive force between the top and bottom Fe3Si layers, which was similarly observed at low temperatures. The soft ferromagnetic layers should be the bottom Fe3Si layer epitaxially grown on Si(111) from the previous study [19,22,25]. The top Fe3Si layer comprising polycrystalline grains and oriented grains with the same orientation relationship with the epitaxial Fe3Si grains in the bottom layer probably has the larger coercive force.…”

“…Recently, Fe3Si has been employed as a spin injection electrode in Co60Fe40/AlOx/Fe3Si tunnel junctions [13] and in spin injection to Si [14]. We have studied spintronics based on a Fe-Si system comprising ferromagnetic Fe3Si and semiconducting FeSi2 thus far [15,16,17,18,19,20,21,22,23,24,25,26]. The combination of Fe3Si and FeSi2 has the following merits [15,16,17,27,28]: (i) the spin injection efficiency might be higher than that in TMR junctions, because the mismatch of the electrical conductivities is less than an order of magnitude, and d electrons contribute to electrical conduction in both layers, (ii) Fe3Si can be epitaxially grown on Si(111) substrates even at room substrate temperature, which is beneficial to the coherent transportation of spin-polarized electrons, and (iii) Fe3Si is feasible for a practical use since it has a high Curie temperature of 840 K and a large saturation magnetization which is half of that of Fe.…”

Film structures of Fe/B-doped carbon/Fe3Si spin valve junctions

“…We have studied Fe-Si based artificial lattices and spin valves comprising ferromagnetic Fe3Si and semiconducting FeSi2, prepared by sputtering, thus far [25][26][27][28][29][30][31][32][33][34][35][36]. Based on the preparation techniques in our previous researches, spin valve junctions comprising ferromagnetic Fe3Si and Fe layers and B-doped UNCD/a-C:H interlayers were prepared, and they were structurally investigated by transmission electron microscopy (TEM).…”

Film structures of Fe/B-doped carbon/Fe₃Si spin valve junctions

“…We have studied Fe-Si based artificial lattices and spin valves comprising ferromagnetic Fe3Si and semiconducting FeSi2, prepared by sputtering, thus far [25][26][27][28][29][30][31][32][33][34][35][36]. Based on the preparation techniques in our previous researches, spin valve junctions comprising ferromagnetic Fe3Si and Fe layers and B-doped UNCD/a-C:H interlayers were prepared, and they were structurally investigated by transmission electron microscopy (TEM).…”