Resistance, magnetoresistance, and thermopower of zinc nanowire composites.

We report a very large enhancement of the thermopower of 4 nm diameter metallic Zn nanowires, with a temperature dependence that is consistent with that of their electrical resistivity and the Mott formula. The temperature dependence of the resistance, magnetoresistance, and thermopower of composites consisting of 15, 9, and 4 nm diameter Zn nanowires imbedded in porous host materials is reported. The 15 nm wires are metallic.

Thermoelectric power of bismuth nanocomposites.

Because of the increase in the electronic density of states in low-dimensional systems, semiconductor quantum wires constitute a most promising thermoelectric material. We report here the first experimental observation of a very large enhancement of the thermoelectric power of composites containing bismuth nanowires with diameters of 9 and 15 nm, embedded in porous alumina and porous silica. The temperature dependence of the electrical resistance shows that the samples are semiconductors with energy gaps between 0.

Geometrical magnetothermopower in semiconductors.

The geometry of a semiconductor sample can be designed to create a very large change of the thermoelectric power in a magnetic field, similar to the effects of the sample geometry on the magnetoresistance. In semiconductors in which the minority carriers have a higher mobility than the majority carriers, this geometrical magnetothermopower can freeze out the contribution of the former to the total thermopower. This opens a new route toward high-efficiency thermoelectric materials.