  Strain-mediated multiferroic composites, i.e., piezoelectric-magnetostrictive
heterostructures, hold profound promise for energy-efficient computing in
beyond Moore's law era. While reading a bit of information stored in the
magnetostrictive nanomagnets using a magnetic tunnel junction (MTJ), a material
selection issue crops up since magnetostrictive materials in general cannot be
utilized as the free layer of the MTJ. This is an important issue since we need
to achieve a high magnetoresistance for technological applications. We show
here that magnetically coupling the magnetostrictive nanomagnet and the free
layer e.g., utilizing the magnetic dipole coupling between them can circumvent
this issue. By solving stochastic Landau-Lifshitz-Gilbert equation of
magnetization dynamics in the presence of room-temperature thermal
fluctuations, we show that such design can eventually lead to a superior
energy-delay product.
