  We investigate different approaches towards a nonvolatile switching of the
remanent magnetization in single-crystalline ferromagnets at room temperature
via elastic strain using ferromagnetic thin film/piezoelectric actuator
hybrids. The piezoelectric actuator induces a voltage-controllable strain along
different crystalline directions of the ferromagnetic thin film, resulting in
modifications of its magnetization by converse magnetoelastic effects. We
quantify the magnetization changes in the hybrids via ferromagnetic resonance
spectroscopy and superconducting quantum interference device magnetometry.
These measurements demonstrate a significant strain-induced change of the
magnetization, limited by an inefficient strain transfer and domain formation
in the particular system studied. To overcome these obstacles, we address
practicable engineering concepts and use a model to demonstrate that a
strain-controlled, nonvolatile magnetization switching should be possible in
appropriately engineered ferromagnetic/piezoelectric actuator hybrids.
