Thermoplasmonic Nanomagnetic Logic Gates

Abstract

Nanomagnetic logic, in which the outcome of a computation is embedded into the energy hierarchy of magnetostatically coupled nanomagnets, offers an attractive pathway to implement in-memory computation. This computational paradigm avoids energy costs associated with storing the outcome of a computational operation. Thermally driven nanomagnetic logic gates, which are driven solely by the ambient thermal energy, hold great promise for energy-efficient operation, but have the disadvantage of slow operating speeds due to the slowness and lack of spatial selectivity of currently employed global heating methods. As has been shown recently, this disadvantage can be removed by employing plasmon-assisted photoheating, where selective local heating is achieved by the polarization dependence of the optical absorption cross section of the nanomagnet. Here, we show by means of micromagnetic and finite-element simulations how such local heating can be exploited to design reconfigurable nanomagnetic Boolean logic gates. The reconfigurability of operation is achieved either by modifying the initializing field protocol or optically, by changing the order in which two orthogonally polarized laser pulses are applied. Our results thus demonstrate that nanomagnetic logic offers itself as a fast (up to gigahertz), energy-efficient and reconfigurable platform for in-memory computation that can be controlled via optical means.