Low temperature junction magnetoresistance properties of Co0.65Zn0.35Fe2O4/SiO2/p-Si magnetic diode like heterostructure for spin-electronics

The magnetic heterojunction diode has been fabricated by growing Co0.65Zn0.35Fe2O4 (CZFO) on well cleaned p-Si substrate using pulsed laser deposition technique, and its behavior under magnetic field is experimentally studied in details. The magnetic field dependent current-voltage characteristics (I-V) have been studied at different isothermal conditions in the range of 5-300 K. The junction shows magnetic diode like rectifying behavior at low temperature, whereas at high temperatures the junction shows nonlinear I-V characteristics. Magnetic field shows a strong effect on junction resistance (CZFO/p-Si). It is interesting that the positive junction magnetoresistance (MR) thus produced, remains very large at low temperature regime (590% at 5 K) and gradually decreases at higher temperatures. In contrast, CZFO magnetic thin film shows negative MR behavior, whereas the junction shows large positive junction magnetoresistance (JMR) behavior throughout the temperature range. The origin of JMR has been best explained by standard spin injection theory. The temperature dependent spin life time (tau) has been estimated for our heterostructure. The value of tau decreases with increasing temperature. The spin life time (183 ps), spin polarization (0.71) and spin diffusion length (375 nm) have been estimated of the heterostructure at 10 K. (C) 2015 Elsevier B.V. All rights reserved.