Demonstration of Bias Dependence of Tunnel Magnetoresistance in Co-MgO-Co Magnetic Tunnel Junctions using First Principles Calculations

This paper reports the bias dependence of tunneling magnetoresistance in Co-MgO-Co magnetic tunnel junctions (MTJs) using first principles SGGA band structure calculations at four different temperatures. The Co-MgO-Co tunnel junction has been simulated at four different temperatures to obtain the I-V and dI/dV V characteristics with parallel and anti-parallel magnetization states, respectively. The TMR ratios have been computed at all four different temperatures. It is seen that temperature doesn't seem to greatly fluctuate the TMR ratios of this magnetic tunnel junction, thereby making it suitable for applications over a wide range of temperatures. For the same four temperatures, the tunnel junction has been simulated for increasing insulator thicknesses. The exponential increase in resistance in both parallel and antiparallel magnetization states has been observed with an increase in the insulating layer thickness. The effect of increasing insulator thicknesses on the TMR ratios at all the four temperatures has also been presented in this paper. The demonstration of bias dependence of tunneling magnetoresistance presented in this paper aptly justifies the application of Co-MgO-Co MTJs in Magnetoresistive Random Access Memories.