  We report the fabrication of one-dimensional (1D) ferromagnetic edge contacts
to two-dimensional (2D) graphene/h-BN heterostructures. While aiming to study
spin injection/detection with 1D edge contacts, a spurious magnetoresistance
signal was observed, which is found to originate from the local Hall effect in
graphene due to fringe fields from ferromagnetic edge contacts and in the
presence of charge current spreading in the nonlocal measurement configuration.
Such behavior has been confirmed by the absence of a Hanle signal and
gate-dependent magnetoresistance measurements that reveal a change in sign of
the signal for the electron- and hole-doped regimes, which is in contrast to
the expected behavior of the spin signal. Calculations show that the
contact-induced fringe fields are typically on the order of hundreds of mT, but
can be reduced below 100 mT with careful optimization of the contact geometry.
There may be additional contribution from magnetoresistance effects due to
tunneling anisotropy in the contacts, which need to be further investigated.
These studies are useful for optimization of spin injection and detection in 2D
material heterostructures through 1D edge contacts.
