First-Principles Modeling of Zn_1-xMg_xO Ferroelectrics

Neuromorphic architectures offer opportunities to optimize the energy efficiency and floating-point-computation performance of microprocessors, beyond the von Neumann computing model in which the data-storage and data-processing functions of the computer are physically separated. The integration of ferroelectric memory capabilities into field-effect transistors requires the development of ferroelectric materials that would be scalable and compatible with current microelectronic technologies. In this work, we study the mechanisms of polarization switching in recently proposed Zn_1-xMg_xO (ZMO) ferroelectric ternaries [1]. The structural and electronic properties of ZMO are predicted from first principles in the composition range of x = 0 to 0.4 at the gradient-corrected and Hubbard-corrected semilocal levels of density-functional theory, showing that the band gap increases with x while the c/a lattice-parameter ratio and the polarization decrease with x. The minimum energy pathways of bulk switching and domain wall migration are determined using nudged-elastic-band calculations, which indicate a significant reduction in the energy barriers and estimated coercive fields for the latter (extrinsic) process.

I would like to acknowledge the Department of Energy for funding this work.