Magnetization dynamics in ferromagnetic coupling interconnect wire using multiferroic logic scheme

Abstract

Nowadays, the intense research effort is focused on exploring alternative emerging device to perform binary logical function. A promising device technology is multiferroic nanomagnet logic. The main reason for the interest in this nanomagnetic switch is its nonvolatility and comparatively low power consumption in combination with the ability to perform logic and storage in one single element. The basic element of multiferroic nanomagnet logic is a sub-100 nm size single domain magnet. Usually, the x-y direction defines the in-plane dimension, while the z axis direction depicts the thickness of nanomagnet. The in-plane magnetizations along easy axis are used to encode binary logic states 1 and 0, respectively; while along the hard axis they denote null logic. The logic operation and data transmission in magnetic logic are realized by the dipole-coupled magnetostatic interactions. In multiferroic nanomagnet logic, the interconnect wire is a very important component since it forms data transmission channel of any nanomagnetic logic circuit. There are two kinds of interconnected wires in this technology, namely antiferromagnetic coupling interconnected wire and ferromagnetic coupling interconnected wire. In this paper, the switching dynamics of a multiferroically and nanomagnetically interconnected wire employing ferromagnetic coupling is simulated by solving the Landau-Lifshitz-Gilbert equation with neglecting the thermal fluctuation effects. The wires are implemented with dipole-coupled two-phase (magnetostrictive/piezoelectric) multiferroic elements that are clocked with electrostatic potentials of 100 mV applied to the piezoelectric layer generating 20 MPa stress in the magnetostrictive layers for switching. Specifically, the ferromagnetic coupling effect model for multiferroic nanomagnet interconnected wire is established, and its magnetization dynamics is simulated by using different stress clocking. It is found that moderate strain (19.7-20.1 MPa) can ensure~180 magnetization reversal, and the logic state is successfully transferred in the ferromagnetic coupling interconnected wire. It is also found that the strong ferromagnetic coupling between multiferroic nanomagnets blocks effective magnetization reversal. This may arise from small spacing-induced out-of-plane magnetization, which does not favor the in-plane magnetization. These findings can provide some guidance for multiferroic logic circuit design.