  We report large anisotropic magnetoresistance (AMR) behaviours in single
lateral (Ga,Mn)As nanoconstriction of up to 1300%, along with large multistable
telegraphic switching. The nanoconstriction devices are fabricated using
high-resolution electron beam lithography of a 5 nm thick (Ga,Mn)As epilayer.
The unusual behaviour exhibited by these devices is discussed in the context of
existing theories for enhanced AMR ferromagnetic semiconductor nanoscale
devices, particularly with regard to the dependence on the magnetotransport of
the bulk material. We conclude that our results are most consistent with the
Coulomb blockade AMR mechanism.

Strongly Correlated Electrons;Materials Science