Magnetic tunnel junctions

Fueled by the ever-increasing demand for larger hard disk drive storage capacities, extensive research over the past decade has resulted in the development of AlOx- and TiOx-based magnetic tunnel junctions that exhibit a large magnetoresistive effect at room temperature. As their commercialization in various applications begins, a new type of magnetic tunnel junction with a crystalline MgO tunnel barrier has emerged that shows a much larger room-temperature magnetoresistive effect. We present a brief overview of the development of magnetic tunnel junctions, introducing the underlying physics. We also discuss two important commercial applications: read sensors in hard disk drives and memory elements in magnetoresistive random access memory. An emphasis is placed on the material aspects of magnetic tunnel junctions.