Magnetotransport phenomena and spin accumulation in MIS structures

Abstract

The present work is devoted to magnetic transport in Fe/SiO2/p-Si, Mn/SiO2/p-Si and Fe3Si/p-Si hybrid structure. For Mn/SiO2/p-Si diode extremely large values of magnetoresistance were observed (105 % for AC and 107 % for DC) which is explained by impact ionization process that can be suppressed by the magnetic field. Lateral photovoltaic effect in Fe/SiO2/p-Si have also shown a strong dependence on the magnetic field in low-temperature region (the relative change of photovoltage exceeded 103 %). In Fe3Si/p-Si spin accumulation was found via 3-terminal Hanle measurements. We believe that the magnetic field affects electric transport through Lorentz force and through the interface states which are localized at the insulator/semiconductor or metal/semiconductor interfaces. Such states play a decisive role in magnetotrasnport as their energy can be controlled by a magnetic field. In Fe3Si/p-Si they also participate in spin-dependent tunneling, causing spin injection from the Fe3Si film into the silicon.