Magnetic anisotropy variations and nonequilibrium tunneling in a cobalt nanoparticle.
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 nonequilibrium spin excitations.
Deshmukh
M M
MM
Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA.
Kleff
S
S
Guéron
S
S
Bonet
E
E
Pasupathy
A N
AN
von Delft
J
J
Ralph
D C
DC