Quasiparticle dispersion in Bi2Sr2CaCu2O8 is investigated with improved angular resolution as a function of temperature and doping. Unlike the linear dispersion predicted by the band calculation, the data show a sharp break in dispersion at 50+/-15 meV binding energy where the velocity changes by a factor of 2 or more. This change provides an energy scale in the quasiparticle self-energy. This break in dispersion is evident at and away from the d-wave node line, but the magnitude of the dispersion change decreases with temperature and with increasing doping.

Tensile deformation behavior of silicon ͑Si͒ wires with nanometer widths, synthesized by nanometer-tip contact and successive retraction, was studied by atomistic combined microscopy of high-resolution transmission electron microscopy/scanning probe microscopy. The elastic limit, Young's modulus, and strength of individual Si nanowires were investigated based on the mechanics of materials at an atomic scale. It was found that both Young's modulus and strength increased to 18± 2 and 5.0± 0.3 GPa, respectively. The elastic limit was 0.10± 0.02 and fracture strain was estimated to be 0.30± 0.01. Experimental results show that mechanical properties of Si wires transform due to size reduction from micrometer to nanometer scale.

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Strong, monochromatic, coherent and continuous terahertz (THz) radiation was generated from the intrinsic Josephson junctions in a cylindrical stand-alone mesa sandwich structure fabricated from a single crystal of the high-temperature superconductor Bi2Sr2CaCu2O8+δ. By varying the base temperature and the dc bias current-voltage characteristic (IVC) points, the emission frequency is tunable from 0.5 to a record high 2.4 THz observed on two inner IVC branch points. Strong emission power peaks were observed at 1.0 THz and 1.6 THz. This device is hence an excellent candidate to fill the “THz gap” between ∼1.4 and 2.0 THz.