MgO(001) barrier based magnetic tunnel junctions and their device applications

Spintronics has received a great attention and significant interest within the past decades, and provided considerable and remarked applications in industry and electronic information etc. In spintronics, the MgO based magnetic tunnel junction (MTJ) is an important research advancement because of its physical properties and excellent performance, such as the high TMR ratio in MgO based MTJs. We present an overview of more than a decade development in MgO based MTJs. The review contains three main sections. (1) Research of several types of MgO based MTJs, including single-crystal MgO barrier based-MTJs, double barrier MTJs, MgO based MTJs with interlayer, novel electrode material MTJs based on MgO, novel barrier based MTJs, novel barrier MTJs based on MgO, and perpendicular MTJs. (2) Some typical physical effects in MgO based MTJs, which include six observed physical effects in MgO based MTJs, namely spin transfer torque (STT) effect, Coulomb blockade magnetoresistance (CBMR) effect, oscillatory magnetoresistance, quantum-well resonance tunneling effect, electric field assisted magnetization switching effect, and spincaloric effect. (3) In the last section, a brief introduction of some important device applications of MgO based MTJs, such as GMR & TMR read heads and magneto-sensitive sensors, both field and current switching MRAM, spin nano oscillators, and spin logic devices, have been provided.