Spintronics for nanoelectronics and nanosystems

The paper will discuss the work related to spintronics, which is being performed in the Western Institute of Nanoelectronics (WIN) and MARCO Focus Center on Functional Engineered Nano Architectonics (FENA). The objectives of the work are to address the use of particle spin as a state variable and to study the feasibility and the implementation of spin-based devices for nanoelectronic applications in order to resolve the major challenges in power dissipation and the variability issues. The work consists of three research areas: nanoscale spin-based devices, coupling of the devices, and benchmark. In this paper, we will first discuss nanoscale spintronics materials in order to investigate new possibilities of creating new spin-based building blocks. These building blocks include nanowires, nanodots and other spin-based materials, which may be integrated onto the silicon platform. In particular, as an example, we will discuss the growth of MnGe (MnSi) by ion implantation and molecular beam epitaxy, and the results of material characterization by X-ray and TEM from these two different approaches will be compared. Magnetic moments of as-grown and annealed samples are characterized using SQUID (superconducting quantum interference device). The paramagnetic to ferromagnetic transition as a function of the hole density is demonstrated. In addition, the electric field dependence in a MOS structure indicates that the magnetic transition may be controlled by electric field, and thus by the carrier density. Spin dynamics of nanomagnets will also be reported. A spin wave bus concept using ferromagnetic films will be discussed for logics and information transfer. We will report the characterization of the spin wave propagation in a ferromagnetic thin film as a function of frequency. The details of the material properties are obtained from these studies in frequency dispersion data. Other principles of nano spin-based devices such as spin torque devices will also be discussed for information processing and storage.