Author: Jonghwa Eom

Publisher:

Published: 1998

Total Pages: 175

ISBN-13:

The electrical properties of mesoscopic AuFe wires have been measured in $\sp4$He, $\sp3$He, and dilution refrigerators. AuFe alloys in this study have Fe concentrations ranging from 0.1 to 0.4 at%, and their spin glass freezing has been observed in the resistivity $\rho$(T) as a function of temperature, which shows a broad maximum at a temperature T$\rm\sb{m}.$ $\rho$(T) of the AuFe spin glass wires has been investigated for wires of various widths in the range of 150 nm-300 $\mu$m. The resistivity $\rho$(T) of the AuFe wires indeed shows a size dependence. As the width of the wire is reduced, the amplitude of the resistivity maximum increases, and T$\rm\sb{m}$ shifts toward lower temperatures. However, the size dependence originates not from some intrinsic spin glass property, but from the electron-electron interaction contribution to $\rho$(T). The four-terminal differential resistance, dV/dI, has also been measured as a function of dc current bias, I. We find that dV/dI becomes asymmetric in I when the width of at least one voltage terminal is less than 150 nm and different from the width of the other voltage terminal. We analyze dV/dI(I) of the AuFe wires by a model heat flow equation, and find that the asymmetry in dV/dI(I) reflects the size dependence of thermopower in mesoscopic AuFe spin glass wires.