Spin transport and temperature-dependent giant positive junction magnetoresistance in CoFe2O4/SiO2/p-Si heterostructure

Abstract

The observation of giant positive junction magnetoresistance (JMR) in our cobalt ferrite (CFO)/p-Si heterojunction has been reported here. The pulsed laser deposition technique has been used for fabrication of the heterojunction. The junction confirms a very good rectifying magnetic diode like behavior at low temperature, whereas at high temperatures the junction shows nonlinear I–V characteristics. The magnetic field-dependent magnetoresistance (MR) of both CFO film and across the heterojunction have been studied in detail. The CFO film shows negative MR behavior, whereas the junction shows large positive JMR behavior throughout the temperature range. The spin lifetime (142 ps) and spin diffusion length (331 nm) have been estimated of the heterostructure at 10 K. The highest JMR value (~1600 %) has been observed at 10 K, and it gradually decreases at higher temperature range. The origin of positive JMR in our heterojunction has been best explained by the standard spin injection theory.