We present detailed measurements of the discrete electron-tunneling level spectrum within nanometer-scale cobalt particles as a function of magnetic field and gate voltage, in this way probing individual quantum many-body eigenstates inside ferromagnetic samples. Variations among the observed levels indicate that different quantum states within one particle are subject to different magnetic anisotropy energies. Gate-voltage studies demonstrate that the low-energy tunneling spectrum is affected dramatically by the presence of non-equilibrium spin excitations.
@article{arxiv.cond-mat/0108166,
title = {Magnetic Anisotropy Variations and Non-Equilibrium Tunneling in a Cobalt Nanoparticle},
author = {M. M. Deshmukh and S. Gueron and E. Bonet and A. N. Pasupathy and S. Kleff and J. von Delft and D. C. Ralph},
journal= {arXiv preprint arXiv:cond-mat/0108166},
year = {2009}
}