The lowest conductance step for a Ni nanocontact is anomalously small in comparison with the large expected number of conducting channels. We present electronic structure calculations for an extremely idealized Ni nanobridge consisting of just a monatomic nanowire. Our calculations show that no less than eight single spin bands cross the Fermi level in a nonmagnetic Ni monatomic wire, dropping marginally to seven in the more stable, fully ferromagnetic state. However, when we build in the wire a magnetization reversal, or domain wall, by forcing the net magnetization to be zero, we suddenly find that d electrons selectively cease to propagate across the wall. s electron propagation remains, and can account for the small observed conductance steps.
@article{arxiv.cond-mat/0111376,
title = {Selective d-state Conduction Blocking in Nickel Nanocontacts},
author = {A. Smogunov and A. Dal Corso and E. Tosatti},
journal= {arXiv preprint arXiv:cond-mat/0111376},
year = {2009}
}