In nanowires, conductance itself can change in a complex nonmonotonic, nonlinear way as a function of current density. For example, see --
"Quantum Suppression of the Rayleigh Instability in Nanowires" http://arxiv.org/abs/cond-mat/0006237 James Bowery wrote: > Something that occurs to me about the emergence of a negative coefficient > of temperature at high loading of hydrogen in metallic lattices is that it > may be related to the stress imposed by that loading. If stress reaches a > point where charge carriers to emerge, then increasing the temperature may > enhance the emergence of those carriers. > > The emergence of charge carriers with stress is theorized to occur in > igneous rock: > > > > *Stress-Induced Changes in the Electrical Conductivity of Igneous Rocks > and > the Generation of Ground Currents* > > *Author*:Friedemann T. Freund, Akihiro Takeuchi, Bobby W. S. Lau, Rachel > Post, John Keefner, Joshua Mellon, and Akthem Al-Manaseer > > *Abstract* > > If we can ever hope to understand the non-seismic signals that the > Earth sends out before major earthquakes, we need to understand the > physics > of rocks under increased levels of stress. In particular we need to > understand the generation of electrical currents in the ground. We have > begun to study how electrical conductivity of igneous rocks changes under > stress and what types of charge carriers are involved. We show that > quartz-rich granite and quartz-free anorthosite both generate electronic > charge carriers when subjected to stress. The charge carriers are positive > holes (p-holes), i.e., defect electrons on the oxygen anion sublattice. > They spread out of the stressed rock volume, the source volume, into the > surrounding unstressed rocks. Time-varying ground currents are required to > generate pre-earthquake local magnetic field anomalies and low-frequency > electromagnetic emissions. We posit that stress-induced activation of > p-hole charge carriers and their outflow from the source volume is the > basic process by which ground currents can be generated in the Earths > crust. We propose that the arrival of p-holes at the Earths surface leads > to changes in the ground potential that may induce ionospheric > perturbations. We further propose that the build-up of high electric > fields > at the ground surface can ionize the air, hence cause ion emission and > corona discharges. When p-holes recombine at the ground surface, they are > expected to form vibrationally highly excited O-O bonds. The de-excitation > of these O-O bonds will lead to stimulated mid-IR emission, which may > explain the reported pre-earthquake thermal anomalies identified in > satellite images. > > *Key word:Pre-earthquake phenomena, Electrical conductivity, Stress, > Magnetic field, Ionization, EM emission, Thermal anomalies* > ------------------------------ > > *Full_Text(pdf)<http://tao.cgu.org.tw/center/article_download_one.php?id=530xv153p437> > * >
