H.P. Roeser

Calculation of the transition temperature of high temperature and bulk superconductors

It is well known and it has been shown experimental evidence that the critical transition temperature Tc of any type of superconductor depends among other criteria on the crystal structure. Very good examples are thallium, mercury, lanthanum, tin and gallium. Also in high temperature superconductor (HTSC) cuprates a relation between the geometry of the crystal and the transition temperature has been found. This investigation of HTSCs with the model of a resonance effect between the de Broglie wavelength of paired current carrying particles and the dimension of the solid state structure forming a quantum well, has been suggested by the authors in a previous paper. In this model the dimension is given by the distance of the atoms providing the current carrying particles and at the same time the structure acts as a resonator stimulating a coherent phase transition from an electron or particle gas to a condensate.

Measurements of fundamental physical constants h/e/sup 2/ and h/2e at 300 K at THz frequencies

Summary form only given. Recent technological advances in detectors, coupling structures, local oscillators (LO) have made it possible to develop low noise heterodyne receivers for frequencies up to 5 THz. When using Schottky diodes with contact diameters below 1 μm and capacitances as low as 0.25 fF the optimum mixing performance demonstrates ballistic electron transport phenomena at room temperature. The mixing current is given by I/sub opt/=N/sub e/eν and the optimum depletion thickness for all different diodes is given by D/sup 2//sub depl/=(h/2e)μ. The voltage across the device as a function of the normalized optimum current for all measurements results in a resistance very close to h/e/sup 2/.