Electrical spin extraction and giant positive junction magnetoresistance in a Fe3O4/MgO/n-Si magnetic diode like heterostructure

Abstract

We have demonstrated here the electrical spin extraction and origin of giant positive junction magnetoresistance (JMR) in our Fe3O4/MgO/n-Si (0 0 1) heterostucture. The heterostructure has been fabricated using pulsed laser deposition technique. The electrical transport properties of this heterostructure have been investigated in the temperature range 10–300 K. The current–voltage characteristics of the heterojunction with and without an applied 6 T magnetic field shows very good rectifying magnetic diode like behaviour throughout the temperature range. The magnetic field dependent JMR behaviour of our heterostucture has been measured in the same temperature range. The heterostructure shows a giant positive JMR at 10 K (∼2279%) that gradually decreases at higher temperatures. The temperature dependent spin polarization, spin diffusion length and spin life time have been estimated for our heterostructure showing a maximum at 60 K (∼0.77, 470 nm and 127 ps, respectively). The origin of the JMR has been best explained by standard spin injection/extraction and spin accumulation theory in n-Si. The JMR value for our heterostructure saturates at a much lower external magnetic field as compared to reported other heterostructures, thus making it a better choice for magnetic diodes in spintronics.