With the motivation of realizing an all graphene-based circuit for low power, we present a reliable nonvolatile graphene memory device, single-layer graphene (SLG) ferroelectric field-effect transistor (FFET). We demonstrate that exfoliated single-layer graphene can be optically visible on a ferroelectric lead-zirconate-titanate (PZT) substrate and observe a large memory window that is nearly equivalent to the hysteresis of the PZT at low operating voltages in a graphene FFET. In comparison to exfoliated graphene, FFETs fabricated with chemical vapor deposited (CVD) graphene exhibit enhanced stability through a bi-stable current state operation with long retention time. In addition, we suggest that the trapping/de-trapping of charge carriers in the interface states is responsible for the anti-hysteresis behavior in graphene FFET on PZT.

We report direct microscopic measurements that confirm the magnetic stripe-domain patterns can be reversibly changed under an electric field due to the converse magnetoelectric effect in a bilayer thin film ferromagnetic-Ni/ferroelectric-lead zirconate titanate $(100\mathrm{nm}∕1.28\mu \mathrm{m})$ heterostructure. Electric field-induced curving, bending, branching, and elongation of magnetic stripe-domain patterns in the Ni layer are observed with the use of magnetic force microscopy. Upon removal of the electric field, the magnetic stripe-domain patterns return to their original configuration, i.e., reversible.

Crystallographic characterization and the ferroelectric properties of 50 nm-thick sputter-deposited Al_0.78Sc_0.22N films deposited at room temperature (RT) and 400 °C are investigated. c-axis oriented growths were confirmed by x-ray diffraction patterns with rocking curve measurements for both samples. Al_0.78Sc_0.22N films were found to grow in the c-axis direction and showed poling-free ferroelectric properties, which are advantageous for practical memory and piezoelectric applications. Although the metal-ferroelectric-metal (MFM) capacitors represent low switching cycle endurance, MFM capacitors revealed remnant polarization (P_r) of 70 μC/cm² and 113 μC/cm² for RT- and 400 °C-deposited samples, respectively. Ferroelectric films with low-temperature process capability can open a wide range of applications.

We report experimental results on a Ni-nanobar/lead zirconate titanate-film magnetoelectric device demonstrating control of a metastable magnetic single domain with an electric field due to the converse magnetoelectric effect (i.e., coupling of piezoelectric effect, mechanical coupling, and magnetostriction). The reversible single-domain evolution from an initial single-domain state to a transitional S-shape domain state with an electric field was experimentally observed with magnetic force microscopy. Upon removal of the electric field, the single domain reverts to its original domain configuration. These results confirm change of a single domain in the nanoscale magnetoelectric/multiferroic device is achievable and subsequent control of local magnetic field is possible.

The effects of field cycling of Al _0.78 Sc _0.22 N capacitors on ferroelectric properties are investigated. In the first hundreds of switching cycles, the reduction in the switching voltage was observed, possibly due to the formation of nitrogen-vacancy to facilitate the atom displacements. With further switching cycles, fatigue effect was observed, especially for domains with low switching voltage. The leakage current analysis indicates continuous downward band bending with the number of switching cycles, effectively reducing the Schottky barrier height for electrons. The breakdown of Al _0.78 Sc _0.22 N films is triggered by the Joule heat due to excessive leakage current. The mechanism is in contrast to conventional ferroelectric materials, where the breakdown is triggered by Joule heat at the local conductive filaments.

We report strain-induced coercive field changes in patterned 300 × 100 × 35 nm³ Ni nanostructures deposited on Si/SiO₂ substrate using the magnetoelastic effect. The coercive field values change as a function of the applied anisotropy strain (∼1000 ppm) between 390 and 500 Oe, demonstrating that it is possible to gradually change the coercive field elastically. While the measured changes in coercive field cannot be accurately predicted with simple analytical predictions, fairly good agreement is obtained by using a micromagnetic simulation taking into account the influence of nonuniform strain distribution in the Ni nanostructures. The micromagnetic simulation includes a position dependant strain-induced magnetic anisotropy term that is computed from a finite element mechanical analysis. Therefore, this study experimentally corroborates the requirement to incorporate mechanical analysis into micromagnetic simulation for accurately predicting magnetoelastic effects in patterned ferromagnetic nanostructures.