Photocontrol of dynamic phase transition in the charge-density wave material K(0.3)MoO(3).

A photoinduced effect has been studied in the quasi-one-dimensional conductor K(0.3)MoO(3). A weak photoexcitation of the sample can drastically affect the dynamic phase transition of the charge-density wave (CDW) motion from slide to creep. The origin of the photoeffect is attributed to a local destruction of the CDW which leads to the photoinduced phase slip and the redistribution of the CDW phase.

Hofstadter butterfly and integer quantum hall effect in three dimensions.

For a three-dimensional (3D) lattice in magnetic fields we have shown that the hopping along the third direction, which normally smears out the Landau quantization gaps, can rather give rise to a Hofstadter's butterfly specific to 3D when a criterion is fulfilled by anisotropic (quasi-one-dimensional) systems. In 3D the angle of the magnetic field plays the role of the field intensity in 2D, so that the butterfly can occur in much smaller fields. We have also calculated the Hall conductivity in terms of the topological invariant in the Kohmoto-Halperin-Wu formula, and each of sigma(xy),sigma(zx) is found to be quantized.