Hybrid spintronics-straintronic nanomagnetic logic with two-state elliptical and four-state concave magnetostrictive nanomagnets

Recently, nanomagnetic logic has emerged as a promising alternative to transistor based logic because it offers both non-volatility and energy-efficiency. In particular, if the switching of the nanomagnets employs “straintronics” [1], whereby the magnetization of a multiferroic magnet is switched with a tiny voltage generating strain in a magnetostrictive-piezoelectric composite, the energy dissipated per bit flip can be reduced to a few hundred kT at room temperature. We had shown, in prior work, that a multiferroic nanomagnet with biaxial magnetocrystalline anisotropy has four stable magnetization orientations that can encode four states (Fig. 1a). Besides doubling the logic density (four-state versus two-state) for logic applications [2, 3], these four-state nanomagnets can be exploited for higher order applications such as image reconstruction and recognition in the presence of noise, associative memory and neuromorphic computing [4].