Experimental demonstration of strain-clocked Boolean nanomagnetic logic and information propagation

Nanomagnetic logic has emerged as a promising alternative to transistor based logic because it offers both non-volatility and energy-efficiency. Recent experiments by Bhowmik et al. [1] demonstrate energy-efficient magnetization switching in nanomagnets using the Spin Hall effect. Another switching paradigm claiming unprecedented energy-efficiency involves magnetization switching of the nanomagnets via “straintronics” [2], whereby the magnetization of a multiferroic magnet is switched with a tiny voltage generating strain in a magnetostrictive-piezoelectric composite (Fig. 1a). This scheme, proposed by our group, was previously shown to reduce the energy dissipated per bit flip to a few hundred kT at room temperature [2-4]. In this work, we show for the first time experimental results implementing some of these schemes, using elliptical magnetostrictive nanomagnets of nominal lateral dimensions ~200 nm and thickness ~12 nm that possess shape anisotropy and are grown on a (001) PMN-PT substrate (Fig. 1b). A voltage is applied along the length of the PMN-PT substrate to generate mechanical strain, via d33 coupling, along the nanomagnet's easy axis of magnetization. The resulting strain-induced magnetization switching is investigated for single-domain nanomagnets and for clocking of dipole-coupled magnet arrays to implement Boolean logic using the schemes illustrated in Fig. 2. The strain clocking schemes used in our experiments are studied with Magnetic Force Microscopy (MFM) that is used to image the single domain magnetization switching and demonstrate strain clocked nanomagnetic logic for the first time [5]. These experimental results will be highlighted in this talk. Preliminary results are included here that show ferromagnetic (Fig. 3b) and anti-ferromagnetic ordering (Fig. 3c) in such nanomagnets.