Lecturer: Jonathan Reiner
Abstract:
Electrons confined to one dimension exhibit various counter-intuitive phenomena such as charge fractionalization, spin-charge separation, and Majorana end modes induced at nanowires rendered topologically superconducting. We study relaxation of hot electrons in semiconducting InAs nanowires through scanning tunneling spectroscopic imaging. By maintaining the MBE grown nanowires under ultra-high vacuum we are able to atomically resolve their facets and spectroscopically investigate the quasi-one-dimensional electronic states in them. We visualize the confined nature of these states both through the Van Hove singularities in their spectrum as well as through direct mapping of the quantized channels via quasi-particle interference. We find that the relaxation of hot electrons in a multi-channel nanowire is markedly slower for electrons in the lowest quantized channel of the conductance band. Focusing on this channel we identify a new relaxation regime of electrons in one-dimension. Above a certain energy threshold the relaxation rate turns non-monotonic where the higher the initial energy of the hot electron is, the more stable it becomes against relaxation. The origin of this unusual energy-evolution of relaxation lies in the form of the Coulomb interaction in one-dimension.