TMR and Al-O based magnetic tunneling junctions

Abstract

AlOx is the most typical barrier material in the early research of high tunneling magneto-resistance (TMR) in magnetic tunnel junctions (MTJs) at room temperature (RT). AlOx is easily formed by oxidizing a pre-deposited Al layer. The MTJ with FM/I/FM sandwich core structure and the spin-dependent tunneling transport properties drew a wide range of interest resulting the so far largest magnetoresistance (MR) ratio of 81% at RT and 107% at 4.2 K in AlOx based tunnel junction. The different types of Al-O barrier based MTJs are Sandwich- Structured MTJ, Spin-Valve Type Pinned MTJ, Double Barrier Magnetic Tunnel Junction (DBMTJ), Half-Metal MTJ, Perpendicular Anisotropic MTJ, Dilute Magnetic Semiconductors Composite MTJ, Superconductors Composite MTJ, Granular Film Composite MTJ and Nano-Ring-Shaped MTJ. A lot of research has been done in this field regarding its practical application in devices and technology. Furthermore, the discovery of Spin-transfer torque (STT) effect is a remarkable achievement in the development process and rapid emergence of spintronics. This effect provides not only a new data writing strategy, but is also consistent with the development trend of high density devices. To reduce the critical switching current is the pursuing target both in lab and industry. The important applications of Al-O based MTJs including Magnetic Read Heads, Magnetic Sensors, Magnetic Random Access Memory (MRAM), Spin Transistors and Field Effect Transistors, Magnetic Logic Devices and Memristors will be discussed in details in this chapter to provide an advanced technological understanding to the readers.