Experimental results on entirely complex oxide ferromagnetic/ferroelectric/ferromagnetic tunnel junctions are presented in which the tunneling magnetoresistance is modified by applying low electric field pulses to the junctions. The experiments indicate that ionic displacements associated with the polarization reversal in the ferroelectric barrier affect the complex band structure at ferromagnetic–ferroelectric interfaces. The results are discussed in the framework of the theoretically predicted magnetoelectric interface effect and may lead to novel multistate memory devices.

Currently, there is great interest in using solid electrolytes to develop resistive switching based nonvolatile memories (RRAM) and logic devices. Despite recent progress, our understanding of the microscopic origin of the switching process and its stochastic behavior is still limited. In order to understand this behavior, we present a statistical "breakdown" analysis performed on Cu doped Ge 0.3 Se 0.7 based memory devices under elevated temperature and constant voltage stress conditions. Following the approach of electrochemical phase formation, the precursor of the "ON resistance switching" is considered to be nucleation -the emergence of small clusters of atoms carrying the basic properties of the new phase which forms the conducting filament. Within the framework of nucleation theory, the observed fluctuations in the time required for "ON resistance switching" are found to be consistent with the stochastic nature of critical nucleus formation.

A comprehensive microstructural study was conducted on optimally-doped epitaxial Ba(Fe 1 −x Co x ) 2 As 2 thin films grown by pulsed laser deposition on various substrates of a wide range of lattice constants: SrTiO 3 , LaAlO 3 , (La,Sr)(Al,Ta)O 3 , MgO, CaF 2 , and BaF 2 . We found that epitaxial strain directly affects the superconductivity in the film, with the transition temperature decreasing linearly with increasing in-plane lattice constant of the film. However, the strain is not determined by the lattice mismatch between the film and substrate. Instead, the mosaic spread of the grain orientation in the film and the thermal expansion coefficient of the substrate were found to correlate well with the in-plane lattice constant of the film. The result confirms the importance of structural distortions to the superconductivity in the Ba(Fe 1−x Co x ) 2 As 2 films.

We present a novel method for creating damage-free ferroelectric nanostructures with a focused ion beam milling machine. Using a standard e-beam photoresist followed by a dilute acid wash, nanostructures ranging in size from 1 µm down to 250 nm were created in a 90 nm thick lead zirconate titanate (PZT) wafer. Transmission electron microscopy and piezoresponse force microscopy (PFM) confirmed that the surfaces of the nanostructures remained damage free during fabrication, and showed no gallium implantation, and that there was no degradation of ferroelectric properties. In fact DC strain loops, obtained using PFM, demonstrated that the nanostructures have a higher piezoresponse than unmilled films. As the samples did not have any top hard mask, the method presented is unique as it allows for imaging of the top surface to understand edge effects in well-defined nanostructures. In addition, as no post-mill annealing was necessary, it facilitates investigation of nanoscale domain mechanisms without process-induced artefacts.