Is spin conserved in tunneling?

[Hyo X]

Say an electron tunnels from one state, through a tunneling barrier, to another state.
Is the spin of that electron preserved (the same before and after)?

If an electron is traveling through a bulk phase conductive metal (a wire), is its spin stable in one state? What will happen to its spin when it hits a scattering site (impurity or crystal defect)?

Is there such a thing as a coherence length - the average length an electron will travel without its spin changing or relaxing? Is this related to the localization length of the electron or the mean free path?

Thanks

 

[UltrafastPED]

This paper may help: http://arxiv.org/abs/1305.1665
"Spin noise spectroscopy of quantum dot molecules"

We discuss advantages and limitations of the spin noise spectroscopy for characterization of interacting quantum dot systems on specific examples of individual singly and doubly charged quantum dot molecules (QDMs). It is shown that all the relevant parameters of the QDMs including tunneling amplitudes with spin-conserving and spin-non-conserving interactions, decoherence rates, Coulomb repulsions, anisotropic g-factors and the distance between the dots can be determined by measuring properties of the spin noise power spectrum.

 

[ZapperZ]

Say an electron tunnels from one state, through a tunneling barrier, to another state.
Is the spin of that electron preserved (the same before and after)?

In most cases, yes. See, for example, Moodera and Mathon, J. Mag. and Mag. Mat. v.200, p.248 (1999).

I say most cases because, in the majority of tunneling phenomena, the spin polarization and conservation are not tracked.

Note also that we have spin-polarized STM devices.

Zz.