  Modulation of stress anisotropy of magnetostrictive nanomagnets with strain
offers an extremely energy-efficient method of magnetization reversal. The
reversal process, however, is often incoherent and hence error-prone in the
presence of thermal noise at room temperature. Occurrence of incoherent
metastable states in the potential landscape of the nanomagnet can further
exacerbate the error. Stochastic micromagnetic simulations at room temperature
are used to understand and calculate energy dissipations and switching error
probabilities in this important magnetization switching methodology. We find
that these quantities have an intriguing dependence on nanomagnet size: small
nanomagnets perform better owing to the fact that they are more resilient to
the formation of metastable states and magnetization dynamics in them is more
coherent. However, for a fixed stress anisotropy energy density, smaller
nanomagnets will also have poorer resilience against thermal instability. Thus,
the challenge in straintronics is to maximize the stress anisotropy energy
density by developing materials and processes that yield the largest
magnetostriction.
