Electric-Field-Controlled Nonvolatile Magnetic Memory Devices

The objective of the modeling task, to be performed under this subcontract, Is to provide theory and modeling support to our circuit deslgn, device development, and materials optimization efforts. It will include investigating MeRAM cells from ab inltio electronic structure calculations and developing strategics for further device performance enhancement and scaling. There are several correlated effects that determine perpendicular anisotropy and VCMA of magnetic interfaces used in MeRAM cells, hence the challenge will be to use theory and numerical studies to separate and quantify' these effects to enable device design strategies. In addition, ab inltio modeling of complex material structures and Interfaces presents logistical challenges in terms of computing capabilities. There is a large set of possible devlce optimization strategies which cannot be explored experimentally In an efficient manner, requiring ab inltio studies both as a guide to experiments and to help in data analysis. This includes questions such as effects of capping, seed layers, strain, and more subtle quantum mechanical effects which play a role in the ultrathin film structures used for MeRAM. This task will be led by Prof. Nick Kioussls. The focus of the proposed ab initio study will be to investigate from first principles electronic structure calculations: (I) the effect of capping or insertion layers on the magnetocrystalline anisotropy (MCA) and (2) enhancing the electrlc-fleld (E-fleld) sensitivity of the MCA (I.e. VCMA effect) of FeCo-based thln films through strain engineering and using heavy metals as a capping or insertlon layer, such as of Hf, Mo, Ru. Pd, Ta, Pt, or Au. The systems to be investigated include: FeCo thin films and MgO/FeCo heterostructures with and without a cap or an insertion layer.