Origin of the low-temperature saturation of the electron dephasing time · revision history

Revision 1

Accepted · first revision · record

Title

Origin of the low-temperature saturation of the electron dephasing time

Plain

Collisions between electrons predict a phase-coherence time that keeps growing on cooling, but many wires and films show it leveling off. Whether trace magnetic impurities explain every such case, or some other source remains, is open.

Precise

In quasi-$1\mathrm{D}$ disordered metal wires, electron-electron interaction gives $\tau_{\phi}\sim T^{-2/3}$ (Altshuler, Aronov and Khmelnitsky). Mohanty, Jariwala and Webb (1997) reported saturation of $\tau_{\phi}$ at low $T$ in Au wires and proposed an intrinsic mechanism; Pierre et al. (2003) found the interaction prediction obeyed in the purest Ag wires and traced saturation in other wires to magnetic impurities at the part-per-million level. Determine whether all reported saturation, including disordered alloy films, oxide films and $2\mathrm{D}$ semiconductor systems, is accounted for by magnetic impurities, radiation heating or other extrinsic sources, or whether a residual saturation remains once these are excluded.

Settled by

$\tau_{\phi}$ measured well below $0.1\,\mathrm{K}$ in films and wires whose magnetic-impurity content is measured independently and whose electron temperature is fixed by noise thermometry, showing whether any saturation survives.

Kind

well-posed

Answer type

identification

References

(empty)

Literature status

partially-resolved

Status note

Magnetic impurities at part-per-million levels account for saturation in Au and Ag wires (Pierre et al., Physical Review B 68, 085413, 2003); saturation in strongly disordered alloy and oxide films has no agreed source.

Posed since

1997