Spin-based devices for future microelectronics

With CMOS technology rapidly approaching its scaling limits, the electron spin attracts much attention as an alternative degree of freedom for low-power applications. Silicon is suited for spin-driven applications because of its long spin lifetime. In confined electron systems the spin lifetime can be increased significantly by uniaxial stress. However, despite the many achievements, an experimental demonstration of a spin-based field effect transistor (SpinFET) is pending due to low spin injection efficiency and difficulties to manipulate spins electrically. This motivates researchers to look into CMOS-compatible spin-driven devices. Spin-transfer torque MRAM is fast, compact, and non-volatile; however, the high current for magnetization switching is a challenge. For in-plane magnetization a substantial reduction of the current is achieved, when the free layer is composed of two parts. In addition to information storing, the same MRAM cells can also be used for information processing, paving a path towards non-volatile logic-in-memory architectures.