Compact computer controlled biaxial tensile device for low-temperature transport measurements of layered materials.

A biaxial tensile device for the transport study of layered materials is described. The device is mounted on the standard 24 pin zero force connector and can be moved between various setups. The compact design of the device makes it suitable for a wide range of studies.

Numerical analysis of surface and edge states in slabs, stripes, rods and surface steps of topological insulators.

By numerically solving the effective continuous model of a topological insulator with parameters corresponding to the band structure of the topological insulator BiSe, we analyze possible appearance of one-dimensional states in various geometries. Massless Dirac fermions are found at the edges of thin ribbons with surface oriented not only along the van der Waals gap but also in the perpendicular direction. Thick rods and slabs with surface steps host massive modes localized on surface faces.

Energy gap revealed by low-temperature scanning-tunnelling spectroscopy of the Si(111)-7×7 surface in illuminated slightly doped crystals.

Physical properties of the Si(111)-7×7 surface of low-doped n- and p-type Si samples are studied in the liquid helium temperature region by scanning-tunnelling microscopy and spectroscopy. Conduction required for the study is provided by illumination of the surface. Application of illumination completely removes the band bending near the surface and restores the initial population of the surface states.

'Quantized' states of the charge-density wave in microcrystals of K(0.3)MoO3.

Quantization of electrons in solids can typically be observed in microscopic samples if the mean free path of the electrons exceeds the dimensions of the sample. A special case is a quasi one-dimensional metal, in which electrons condense into a collective state. This state, a charge-density wave (CDW), is a periodic modulation of both the lattice and electron density.