T. Katsufuji

Large Kerr effect in bulk Se-based chalcogenide glasses

High-speed optical communication requires ultrafast all-optical processing and switching capabilities. The Kerr nonlinearity, an ultrafast optical nonlinearity, is often used as the basic switching mechanism. A practical, small device that can be switched with ~1-pJ energies requires a large Kerr effect with minimal losses (both linear and nonlinear). We have investigated theoretically and experimentally a number of Se-based chalcogenide glasses. We have found a number of compounds with a Kerr nonlinearity hundreds of times larger than silica, making them excellent candidates for ultrafast all-optical devices.

Electric-field-induced resistance switching universally observed in transition-metal-oxide thin films

We show that polarity-dependent, nonvolatile resistance switching by electric field occurs in the thin film of various transition-metal oxides in almost the same manner. This result indicates that, contrary to the general acceptance, perovskite manganite is by no means a special compound for this phenomenon. It is also suggested that the resistance switching is not dominated by a detailed electronic structure of each sample, but dominated by a more general origin, e.g., crystalline defect.

Impurity Effects on the Electronic/Magnetic Ground States of Perovskite Manganites.

Impurity effects on charge ordering (CO) as well as magnetic ground states in perovskite-type manganites are investigated. We found that the CO state becomes short-ranged with a small amount of imp...

Stripe order at low temperatures in La2-xSrxNiO4 with 0.289-x-0.5

The stripe order in

Frustrated Magnetism and Cooperative Phase Transitions in Spinels

{\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{NiO}}_{4+\ensuremath{\delta}}

Charge Ordering in the Geometrically Frustrated Spinel AlV2O4

with

Role of intrinsic disorder in the structural phase transition of magnetoelectric EuTiO3

0.289\ensuremath{\lesssim}x\ensuremath{\lesssim}0.5

Structural and Magnetic Properties of Spinel FeV2O4 with Two Ions Having Orbital Degrees of Freedom

was studied with neutron-scattering technique. At low temperatures, all samples exhibit hole stripe order. Incommensurability

Electric-pulse-induced reflectance change in the thin film of perovskite manganite

\ensuremath{\epsilon}

Strong self-phase modulation in planar chalcogenide glass waveguides

of the stripe order is approximately linear in the hole concentration