Doping Mediated Electronic Structure Modulation and Carrier Injection-induced Spin Filtering in Magnetic Tunnel Junctions

This study examines the effect of Zn doping-induced band structure modulation on tunnel magnetoresistance (TMR) of Fe/Zn-doped MgO/Fe (3.125% and 6.25% Zn doped) magnetic tunnel junctions (MTJs). The simulation considers nonequilibrium Green’s function (NEGF) assuming spin precession at Fe/MgO spin injection interface of the devices. MgO optical gap has been observed to reduce significantly resulting in carrier injection process along with tunneling mechanism in these devices. Carrier injection process incorporates spin filtering especially in antiparallel orientation of the device at negative bias. Change in spin transport process from carrier tunneling in parallel to carrier injection in antiparallel orientation resulted in significant TMR response upto 1200% at room temperature. The incorporation of voltage insensitivity along with high TMR signal can be utilized in these doped MTJs for data storage applications.