Investigation of the monopole magneto-chemical potential in spin ices using capacitive torque magnetometry.

The single-ion anisotropy and magnetic interactions in spin-ice systems give rise to unusual non-collinear spin textures, such as Pauling states and magnetic monopoles. The effective spin correlation strength (J) determines the relative energies of the different spin-ice states. With this work, we display the capability of capacitive torque magnetometry in characterizing the magneto-chemical potential associated with monopole formation.

Modification of spin-ice physics in thin films.

We present an extensive study on the effect of substrate orientation, strain, stoichiometry, and defects on spin-ice physics in thin films grown onto yttria-stabilized-zirconia substrates. We find that growth in different orientations produces different strain states in the films. All films exhibit similar -axis lattice parameters for their relaxed portions, which are consistently larger than the bulk value of 10.

Atomic-Scale Mechanisms of Defect-Induced Retention Failure in Ferroelectrics.

The ability to switch the ferroelectric polarization using an electric field makes ferroelectrics attractive for application in nanodevices such as high-density memories. One of the major challenges impeding this application, however, has been known as "retention failure", which is a spontaneous process of polarization back-switching that can lead to data loss. This process is generally thought to be caused by the domain instability arising from interface boundary conditions and countered by defects, which can pin the domain wall and impede the back-switching.

Strain Doping: Reversible Single-Axis Control of a Complex Oxide Lattice via Helium Implantation.

We report on the use of helium ion implantation to independently control the out-of-plane lattice constant in epitaxial La(0.7)Sr(0.3)MnO(3) thin films without changing the in-plane lattice constants.

Understanding Strain-Induced Phase Transformations in BiFeO Thin Films.

Experiments demonstrate that under large epitaxial strain a coexisting striped phase emerges in BiFeO thin films, which comprises a tetragonal-like (') and an intermediate ' polymorph. It exhibits a relatively large piezoelectric response when switching between the coexisting phase and a uniform ' phase. This strain-induced phase transformation is investigated through a synergistic combination of first-principles theory and experiments.