Deterministic control of magnetism by the multiferroic magnetoelastic effect at the nano- and micro-scale

Ferromagnetic materials are being incorporated into a wider range of emerging applications of nanotechnology, which include memory, nanotweezers, microfluidics, and biomedical applications. These newer applications exploit the favorable scalability of the permanent magnetic diploes due to their relatively large energy density, in addition to their compatibility with fluidic environments. Previously, two major approaches have been studied to adapt magnetism at the nanoscale/microscale: scaling current-based magnetic coils, and employing external magnetic fields. However, Joule heating causes significant limitations in current-based magnetic devices, as devices are miniaturized below the microscale due to reduced efficiency and challenges of heat dissipation. Use of external magnetic field control requires external magnetic sources such as permanent magnets or electromagnetic coils, which do not provide control at the individual element-level control and limit overall system scalability. Therefore, control of magnetism is one of the major challenges when scaling magnetic systems below the microscale This work demonstrates a new approach to control of magnetization, or magnetic states in ferromagnetic structures using electrically generated strain. Strain coupling can be achieved by building ferromagnetic structures on piezoelectric substrates, which are called multiferroic heterostructures. Magnetic states at the nano- and micro-scale are investigated with finite element analysis (FEA) models. The magnetoelastic coupling of the magnetic states and electrically generated strain are numerically predicted by a FEA that fully couples Landau-Lifshitz-Gilbert micromagnetics with elastodynamics. This simulation results are validated by X-ray magnetic dichroism photoemission microscopy (XMCD-PEEM), and magnetic force microscopy (MFM). This work provides a new pathway to develop energy efficient magnetic manipulation techniques at the nanoscale