Time-Resolved X-Ray Powder Diffraction Study of Photoinduced Phase Transitions in Ti O Nanoparticles.

Nanoparticles of Ti O have been reported to show a permanent photoinduced phase transition at room temperature. This suggests that light-induced phase transformations of Ti O nanoparticles may be promising for technological applications. Here, we report a photoinduced semiconductor-to-metal phase transition from β-Ti O to λ-Ti O nanoparticles at room temperature observed directly by time-resolved X-ray powder diffraction in a pump-probe setup.

Rashba coupling amplification by a staggered crystal field.

There has been increasing interest in materials where relativistic effects induce non-trivial electronic states with promise for spintronics applications. One example is the splitting of bands with opposite spin chirality produced by the Rashba spin-orbit coupling in asymmetric potentials. Sizable splittings have been hitherto obtained using either heavy elements, where this coupling is intrinsically strong, or large surface electric fields.

Observation of layer-breathing mode vibrations in few-layer graphene through combination Raman scattering.

We report the observation of layer-breathing mode (LBM) vibrations in few-layer graphene (FLG) samples of thickness from two to six layers, exhibiting both Bernal (AB) and rhombohedral (ABC) stacking order. The LBM vibrations are identified using a Raman combination band lying around 1720 cm(-1). From double resonance theory, we assign the feature as the LO+ZO' combination mode of the out-of-plane LBM (ZO') and the in-plane longitudinal optical mode (LO).